Week 1: Chapter One – Why we Program?

Hello, my name is Charles Severance. I’m a Clinical Professor at the University of Michigan
School of Information, and I’m your instructor
for this course. This course is a
little different than every programming
course that I’ve ever taught, or I’ve ever taken. This course is dedicated to the notion that
every single person on the planet needs
to be able to write programs and can write programs. You do not have to
have a bunch of math. I do not expect math. I do not expect that you’ve taken any other programming classes. I don’t expect you know
anything about computers. I think no matter
what your background is, you can program. That’s why it’s called
Programming for Everybody. I have
a couple of goals. Certainly, I want to
teach you how to program. But actually what I
really want to do is teach you how to take
a programming class because it turns out that most of the other programming classes
in the world are kind of difficult. They sort of assume way too
much and the teachers sort of don’t even realize how much they’re expecting from students. So when you’re done
with this class, you can go and take
another beginning class. And that way you have this as an on-ramp to all of your
programming activity. And so I’m really excited
that you’re here. Another thing that I
want to do is I want to teach you how to be a mentor. I want to teach you how to
be a teacher of programming. So I want you to
take all my ideas, and I want to you to
help the next person. And the reason is that
learning how to program is a little sort of foggy, uncomfortable, you
get stuck on things, and those things aren’t
hard, I assure you. But when you’re stuck on them, they feel really hard. And the best way to get unstuck is get some help from somebody. And if they’re sitting
right next to you, and they can go, “Oh look. You’ve just got to like add
two spaces and it’s fine.” And you’re like, “Oh, that
saved me a lot of time.” So I want you to be willing
to help somebody else. Another thing that’s
important to me is that I want to create
more teachers. Whether they’re at universities,
or community colleges, or high schools, or
even middle schools, or in professional situations. I have given you all of the materials for
this course at a website. They’re all licensed
under Creative Commons, the slides, the autograders. I want you to in a sense
adopt this textbook, and then use
my teaching kit so that you can become a teacher
of this material, because I don’t think that I’m naturally the only
teacher of this. And in particular, if you don’t speak English as
your first language, you might want to teach this class in
your native language. And so that’s another reason
that I give you these materials with a free and open copyright
that you can take them, you can translate them
into your language. The book has been translated
into several languages. And that’s really exciting. Those books that have
been translated are usually free and available. You can get print copies
that are very inexpensive and
all the ecopies are free. And so this notion that
I create this kit, that you can then change the kit. You don’t have to
just take my class. You can change it and you can make it work for you locally. And really, the overall
goal of this is more than just like teaching
you one programming class. I think that the entire
technology marketplace, and to some degree all of business in general is becoming
increasingly technical. And too many people, young, old, regardless of education,
are shut out of this sort of club where you need to know something
about technology. And so that’s why we’re
Programming for Everybody. Regardless of geography,
regardless of ability to pay, regardless of if you
have any disabilities, I want Programming for
Everybody to be everybody. I want when to just expand forever the number of people who are capable
of programming. It’s an open
self-sustaining ecosystem, and have you be part of
that self-sustaining ecosystem. So again, welcome to the class. I look forward to what
you do and I look forward to seeing you
throughout the class.

[MUSIC] I’m Guido van Rossum. I created the Python language. I have worked on Python for 25 years and I have worked with a large group of
others of course in the Python community. I’m very excited to see
you all in this class. And I’m very proud that you’re
using my language to learn. Python is just the first step you’re
setting on the path to programming. There are many exciting things
to learn in programming. Many that you can learn using Python, many
that you can learn using other things. And you won’t be alone. There will be millions of people
who have gone before you or, or who are learning Python
at the same time as you. And you, you can help each other,
and you can learn together. [MUSIC]

Hello, and welcome to Python for
Everybody. My name’s Charles Severance and
I am your instructor. We named this Python for Everybody because
we are dedicated to the notion that increasingly as our lives
are surrounded by technology, that we want you to become a maker of technology,
not just a consumer of technology. We want to change your
perspective from this side of technology where you are looking at it,
to the other side where you’re back here. You are like a creator of the technology
and you can create things. And it takes a long time and you may not
want to be a professional programmer ever, you might just like read
a little bit of data, but we believe that everybody should
know basically how to program and how to get things done inside of
a computer, just as much to just be a responsible participant in a modern,
increasingly technically oriented society. Computers want to be helpful. They are programmed, they are designed,
the hardware’s designed. We’ll talk about hardware
in the next segment. But it’s designed and wired, and
when you apply electricity to it, it basically has one question, and
that is what do you want to do next? And if you think about your phone and
all the apps that you have on your phone, each app is like what to do next,
what to do next. So, as a programmer,
your job is to serve the user. The user has something they want to do. Maybe they want to zing a bird towards
a pig or maybe they need to analyze some data, or maybe they want to do
something like talk to their phone and you have to be a real
advanced computer scientist. And so, as a user we just have so
many wonderful programmers who have put so much software that make
these phones intelligent. The hardware itself is
not all that intelligent. And our job as programmers is to act as
intermediaries between the hardware and the user to build something wonderful and
beautiful. And so, you can kind of imagine
that your job as a programmer is to intermediate between
the hardware and the end user. And if you’re a professional programmer
and you’re trying to sell your software, well, you’re trying to imagine
what the world might want. And you could imagine all
these app stores, etc. And these are places that
you can build software, and exchange that software with
other folks, and help people out. And like I said,
we are trying to flip you from one side of this device to the other side
of this device, where you are the maker. And you can think of this as
a tool to manage your calendar, or drive your car and
read a map, or whatever. But when you look at it
from the other side, when you look at it from being
a programmer, you use things like compilers and interpreters and programming
languages and networks, etc. And we actually have tools that
we are going to learn to use. Python is a tool that the programmers
on the back side of this computer use to make new things for
the front side of the computer. Now, what’s your motivation
to become a programmer? Well, the kind of gross motivation for professional programmers is to build
something for everyone else to use. Like I worked on this open
source software called Sakai, which millions of people use around
the world, teaching and learning. It’s very rewarding for me. I feel really good about that. You might build a guest book for
a website. But that’s generally not the first
thing that you’re going to do with your programming skills. You might get some data. You might be an accountant. Or you might be a lawyer. Or you might be a librarian. And somebody’s got some data and
you can’t get a report out of this data, it’s something you’re
really curious about. Somebody says can you knock out
a little piece of Python code to count up the number of times
that this happens on Saturday, but then it also happens again on Monday. Tell us how many times that happens. And so you write 40 lines of code and it
comes out and tells us what that data is. And that’s really useful. The key difference between writing
a program for someone else and writing a program kind of for yourself to consume
or just a few other people is the rigor. You don’t have to be such a professional just to write code that
you can use yourself. If it works and it gets you
the data you want, then job done. If you want to become
a professional programmer, then you kind of have to study how to
be more precise and more engineering. But we’re not going to worry about
that in this beginning set of courses. We just want you to learn the mechanics
and the language of programming. And so we kind of want to take you,
like I said, from being a user to being a programmer. And as a programmer, you start thinking
of yourself as living inside the computer. So you’re a consumer out here. You’re clicking on buttons and stuff. And so as a programmer, you’re going to
write code and that code is going to use data, networks, and CPUs, and memory, and
then do something for the user. So we’re trying to change your perspective
and sort of pull you into the computer. Well, what are you doing in that computer? What’s code?
What’s software? What’s a program? Well, a program is like a sequence
of stored instructions. And the idea is that the computer itself at the
lowest level in the hardware is just not that smart. But it has a lot of flexibility in that
if we give it the right instructions, it can do amazing things. If we give it right instructions to
listen to voice, digitize the voice, and make sense of the voice, then you can write
a program that can “hear”. The computer doesn’t hear,
the program hears. The computer makes it so that it can run
all the calculations that seems to make it hear, but a human being or
actually thousands of human beings made it possible so
that you could talk to your phone. And so you can think of, at the far end
of this, when you’re building something really brilliant like the ability for
a computer to listen to you, you are taking you, and all your
creativity, and all the research that you’ve done and you’re building something
really amazing and put it in the computer. But it is still a stored series of
instructions that runs step by step, and someone figured out every single
little step that has to happen. And so once we figured this out, we write the instructions carefully and
then we give it to somebody. Here is a program that
does voice recognition. And if you’re interested in it,
I say it’s wonderfully creative. As a professional programmer,
I have loved my life. I have loved the kinds of things that
I do, that I build things for people. And I make them happy, and
then I sort of feed off of that and then I build something else. But ultimately it’s just
a set of instructions. If you’re like,
what’s in a set of instructions? Well, here we go. Here is a program for a human being. Now I may be showing my age a little bit,
but this is a YouTube video. Hopefully, it’s not taken down
by copyright or whatever. On this song called the Macarena. And so, the Macarena is an algorithm or
a series of steps that hopefully you, five years ago or many years ago
you would got to the bar and you’d watched all these
people doing these things. Putting their hands up and putting their
stuff around, and wiggle, wiggle, wiggle, and turning around, right? And you’re sitting there,
and you’re like okay, what’s the sequence of
instructions that you’re doing? As a matter of fact,
there’s a looping thing. As long as the music plays,
you put your left hand out, you put your right hand out. You flip your left hand. Flip your left hand, flip your right hand. I forgot all about it. But, here’s something I want you to do. I want you to look at this slide. Now, I’m going to be quiet for a minute. I want you to look at this slide,
pause the video if necessary. This, there are three
bugs in this program. It looks right, but there are three bugs. So I’m going to stop for a second. So hopefully you paused, if you had to. But now I’m going to come back and
I will show you what the bugs are. And here are the three bugs. Now if you didn’t find them,
even if you looked closely, you have learned something
about human beings and that is that we human beings
operate in an error-filled world. There are typographical errors,
people say things incorrectly. And we as people just fix them as we’re
perceiving them, as we understand them. But even as you read this,
you might not have seen these mistakes, because your brain just fixed them because
we just fix errors in our environment. It’s what we do. Computers aren’t like that,
they are not like that. Although voice recognition,
after a while, that software does learn how to filter out errors, but
that was really hard to write, okay? Computers do not understand how to filter
out errors, but with enough instruction, you can kind of get them
to filter out errors, okay? And that’s why search
engines kind of work, they’re, it’s sort of a soft intelligence,
but it was really hard to build. But when we start talking
about writing programs, whether it’s writing programs
to do search engines or writing programs to do voice recognition,
those programs have to be perfect. They make the tiniest text
contextual or typographical error. those programs simply do not work. And so, here we go. So here we say right ham
to the back of the head. What? Where was there ham in this? So you got this ham in your hand, and
you went, hit in the back of your head. You may not notice this, but the computer is literally going to say,
syntax error, I quit, right? And so, syntax error is the moment
where the computer says to itself, I don’t know what to do. And the same thing is true here. I gotta hit somebody,
what are you talking about? And so the computer is going to
be completely lost by this. You might look at this and you might
just fix it and compensate for it. So that’s sort of a little set of
programming, programs for people. So that’s the code that’s right. So, let’s talk a little bit
about programs in Python. Like I said, it’s a set of instructions.
So I’m want to put up some text here and I want you to count the number
of each word in this text and then tell me what’s the most common word
is and how many times this word occurs. Here we go. Count, just count, concentrate,
concentrate, concentrate, concentrate, and part of
the interesting thing here is not so much whether you can count those words or
not, but how your mind is actually reacting to
the problem that I just placed you in. You’re probably like, ooh,
this is just not good. I’m so good, I can drive a car, I can
play baseball, I can catch something. I can sing a song. And yet to be focused on counting these
words seems really, really annoying. It turns out this is one of those things,
text analysis, is one of those things that computers are really good at and
we humans are really bad at. So it’s really great to delegate
this problem to a computer, if you know the language of the computer
and you can talk to the computer. And so,
I don’t expect you to look at this code. We’re going to spend many weeks looking
at all the basics of this thing, but this is a program. This is a set of instructions, it’s got
two, six, about 11, 12 lines of code. And in it, we have instructed the computer
to read through a bunch of text, count the words, and
tell us what the most common word is. And so if we run this program,
and we give it a file of words, it’ll say the most common word is
“to” and there’s 16. That clown.txt that I just asked you,
“the” is the most common word, and there are seven of those. And so, this is a, this is basically an outline of a program,
that, I mean, it is a program that gets
solves this problem that we will learn about. So, don’t try to learn this right away. Up next, we’re going to talk about
the hardware architecture and what goes on inside the computer that you’re going to
make use of as you become a programmer.

Welcome back. Now, we’re going to talk a little
bit about hardware architecture. You might ask yourself sort of
why all these terms, and words, and central processing unit, what I
want from this section is I just want to define a few terms, so that I can
use them in the rest of the course. That’s really it. I want you to have some sense of
the basic block diagram of things. Now in the old days, I’m going to show
you three generations of hardware. I’m going to show you really old
hardware from the 60s and 70s. I’m going to show you sort of medium old
hardware from the 90s and early 2000s. And then, I’m going to show
you sort of super brand new hardware that sort of this
is a Raspberry Pi and it’s the kind of highly integrated hardware
that goes into things like the cellphone. So I’ll kind of be going back and forth between three complete
generations of hardware. But the picture and the concepts that I
want you to understand are these terms. Central processing unit,
main memory, secondary memory unit, and input/output devices. So we’ll start with
input/output devices. They are the way that this computer
accesses the outside world. So things like the mouse, the keyboard,
right, I got a keyboard here. Keyboard. Screen. All these things. I don’t want to mess
up the keyboard there. And so these are the input/output devices. There is a little, that’s okay just mess
up a little bit, no problem at all. Output devices, screens, and that’s sort of how the humans in
the outside world interact. Software, the main inside the computer,
we have the central processing unit, and the main memory, and
then the secondary memory. And so it’s probably easier for
me to take the, neither the oldest nor the newest, to give you a sense
of what is going on here. And so, if you had a desktop and maybe you
still have one of these junky old desktops at home, they are the ones that are big
and they make noise when they start up, they have in them a number
of different parts and the closest thing that a computer
has to intelligence is this. Central processing unit,
CPU is what we call them. And if you look at the back side of
this CPU it is actually a circuit. It’s a highly sophisticated circuit
with millions of transistors on it, and you’ve probably heard that,
millions of transistors. It runs maybe three billion
instructions per second. What does that mean? Well that means that an instruction
is a set of electrical pulses, maybe 32 little wires or 64 little wires. And at three billion times a second,
this is programmed to ask what’s next. And it pulls what’s next in
these little electric wires. Well, where does it get
the answer to what’s next? It gets the answer to what’s next out
of the memory. And so your program, when you write a program, let me
draw this, when you write a program, you create a file on the secondary memory,
like a Python file, and then at some point that is loaded into the main memory,
translated, and then your program is here. And then when the CPU says what next,
your program feeds its first instruction. And then when that’s done,
the CPU says what’s next? It feeds the second instruction,
third instruction, fourth instruction. It’s called the fetch-execute cycle. And these two parts, the CPU and
the main memory, are what participate. And the main memory is
where you kind of live. Somewhere in there, a little tiny
version of yourself is in there answering the questions
that this is asking. Now you might say how smart is this,
it’s not really very smart at all. It’s a really fast hand calculator with lots of
storage is the best way to think about it. And going back to the 60s and the 70s, this is a piece of hardware from
a computer that was the size of a room with probably 20 refrigerators,
all with modules that make this up. And in here, well you probably
can’t see it, you’ve got resistors, transistors, and
capacitors, and then wires. The wires are all printed on this printed
circuit board, otherwise known as PCB. And so, the closest thing this has to
intelligence are these transistors. And at their simplest, what they can do is they can sort of
make really simple yes/no decisions. And then they also can be used,
if you hook them together the right way, to store a little bit of information. And so, when we say there
are millions of transistors packed into this little
tiny square right here. It’s kind of pretty. I mean, if you look at it, it’s sort of,
it looks almost like a jewel, it’s so pretty. And each one of those is a real
tiny photo-imprinted transistor and so there are millions of this. And so the difference between 1960 and today is this part gets smaller and
smaller and smaller to the point where literally thousands of these things
are all squeezed in to that little square. And coming back to sort of the mid-grade
one, so this one here is the motherboard. This part here is the motherboard because
it’s the mother of all boards and it connects everything together. All these components plug in and
that’s how they are connected together and there’s a whole bunch of wires that
go back and forth on this and so this is how your program in a sense is
transported from the memory to the CPU. And so, this motherboard connects them. Another thing that’s connected to
the motherboard is secondary storage. Now, the reason we have to have
secondary memory or secondary storage is this is designed to be really fast,
the main memory is super fast. And what happens is when
the computer turns off, your program is erased from here. And so I originally said that
you write your program, and you put a file in here, a .py file, and this is the same place that your Word
files are, and your PowerPoints are. And then, the .py file is kind of loaded
and translated into the main memory. And then when the computer shuts off,
all this data goes away. Secondary memory is permanent. This does not get shut off. And so, in the old days,
this old-day stuff, we used to store our programs and
our files on our hard drive. And you may even have a computer at home where there’s a actual physical spinning
platter of magnetic media and a little head that goes in and
out to read and write the data. And so it actually records
magnetically when you put a file in, it records it and then when the power’s
off the magnetic recording stays here. And so these things,
physical disk drives, are kind of going, becoming extinct, because all the data
is in little USB sticks like this, and that’s a perfectly good
version of secondary memory. But at least for us,
we can look at these beautiful antique mechanical gadgets that we used to store
data magnetically when the power goes off. Now, this one here is pretty broken. [LAUGH] And it’s pretty in bad shape, so it’s probably not really
storing much of anything. So in a summary of this picture, the thing I really want you to get out of
this picture is a series of definitions. The Central Processing Unit
is very simple, it’s the closest thing
computers have to brains, but it wants to answer the question what to
do next, but we have to feed, through memory. the answers, which is your programs.
And then we have input devices, output devices, the main memory, and then the larger permanent
storage in the secondary memory. So, where you live inside of a computer
is basically in the main memory. When you write a program, you type it in
the computer, you outside the computer are typing on your keyboard, and
you’re typing Python commands into a file. Like if x less than 3, print, right? And then, that gets loaded into the
main memory, and so you,
this is a creative version of yourself. It’s your instructions that
are going to be run and that program ends up in the main memory,
and then it’s run. So, this is sort of where you
live inside the computer. Think of it that way. You’re living in main memory when
your program is actually executing. Now, it turns out that
the instructions that this central processor uses
are a series of zeroes and ones. And when I said like 32 zeroes and
ones, or 64 zeroes and ones, simultaneously are fed into this for
each of the instructions. We use a language called machine language. And I would love some day to
teach you machine language, but we don’t have time right now, and you,
that is more moving towards being a computer scientist when you start
learning machine language, but basically we don’t have to worry
about that too much, we write Python. And we write in Python and then something effectively translates
it into machine language and then machine language is the thing that
runs and runs and runs and runs and so. Someday you might take a look for that,
but that’s more of a computer science thing and
the software that does this translation, which is either called a compiler or
an interpreter, we can talk more about that when you
become more of a computer scientist. But for now, we’re going to worry
about how to write this code and the rest of this sort is going to fall
by the wayside as we go forward. So, I got a couple of videos here. This one video,
hopefully the YouTube URL is still good, if not we’ll try to find another way
to get you linked to a good copy of it. But it, basically, these, as I said,
there are millions of transistors in one of these things, and there’s a lot
of electricity going through these things. And when your computer
heats up on your lap, it’s this little part here
that’s working really hard. Its doing things three billion times a second. So someone has made a video,
not a very good video, but it’s from a long time ago,
where you take the cooling part off and you watch what happens to these CPUs when
they’re doing all this work three billion times a second using all this electricity
and they’re not properly cooled. Another cool video that we have
is a video of hard drives and how they actually spin in reality. This one is totally messed up because
I’ve been beating on it for years and playing with it, using it in all my
classes for years, so it’s in really bad shape. But this video shows you how that works
and how it actually spins in reality. And you’ll hear noises that if
you have or had a desktop computer, you’ll kind of recognize the noise, and
then you’ll have an idea of what’s going on inside that computer as that
secondary storage is moving around. And like I said, secondary storage is
becoming less and less relevant as we move to solid-state storage, like the kind
of storage that’s in a USB stick. So up next, we’re going to talk
about how we write that Python. I talked a little about the hardware now,
and now we’re going to get
started writing some Python.

[SOUND] So now we’re going to talk
about Python as a programming language. You probably noticed that
I’m wearing a sorting hat. The reason I’m wearing a sorting hat
is that where I work at the University of Michigan School of Information, we
are in a building called the North Quad. And you can look it up on Google and
find a picture of it if you like. And I think it’s designed
to be like Hogwarts. It’s got a little center,
it’s got this outside bit, it’s got a really cool cafeteria that
looks like owls might fly through it. And so we moved to this a few years
back when I started teaching Python. And I was teaching my very,
very first class in this building, which we’ve sort of lovingly called
Quadwarts, because it’s North Quad and we thought it was kind of like Hogwarts. And so, I’m joking, and
I wore my robes to class, and I said welcome to Quadwarts,
and you have to wear your robes every time to class,
and I was being funny. And I said okay, it’s our first class,
we’re teaching Python, and let’s do a sorting ceremony. I didn’t have the sorting hat back then,
so I have a sorting hat now. And so, that’s cool. And I’m like,
I think I’m going to be in Gryffindor. And they told me, the students said
that I couldn’t be in Gryffindor. And I’m like,
why can’t I be in Gryffindor? Everybody wants to be in Gryffindor. And they told me that
I was teaching Python. Python is like a programming
language that’s based on a snake. And even worse, my name’s Charles
Severance, and I’m like Severus Snape. And so they basically told me
that I had to be in Slytherin. And so since then, I’ve bought many
Slytherin items, I got Slytherin wands, when I graduate,
you’ll see my Slytherin wand. I got a sorting hat, so you’ll see me
drinking tea throughout the class, from my Slytherin cup and so I guess
I’m just doomed to be in Slytherin. I don’t know if that means I’m a good guy
or a bad guy, or a good guy that seems like a bad guy or bad guy that turns
out to be a, right, it’s a lot of book. So, the whole thing about being in
Slytherin is that you can talk to snakes because you can talk this weird
language that others don’t understand. Python’s like that. Python’s a language that
most don’t understand. You, of course,
will begin to understand it. It’s a weird language, it’s strange,
it’s not easily understood by others. We call ourselves Pythonistas. And Guido van Rossum, over 20 years ago,
invented this Python language that we have grown to know and
love, and has become so important. And while I’m going through
all this like snake stuff, it turns out that that is not at
all why Python was named Python. Python was not named for a snake even though we use
the snake motif all the time. It turns out that what Python was named
for was Monty Python’s Flying Circus. And the reason was is that Guido was
trying to capture an air of play. Most programming languages in the 80s
when Python started were very, very serious, and very complex and you had
to be really serious to figure them out, a lot of math geniuses. And Guido thought, I could probably
write a programming language that wouldn’t be that hard,
would be fun actually, would be enjoyable to use, but
let’s not make it bad. Let’s not make it weak,
let’s make it both powerful and enjoyable. And so that’s why Python turns
out to be such a perfect language to use as your first programming language,
is that it’s designed to be your first programming language but
it’s also powerful. So many times you build a first
programming language that’s weak. And not capable of doing a lot of stuff. But Python has this wonderful,
easy to learn and powerful and useful. And so there we are. Welcome to being a Pythonista. Now. As you learn Python, remember, you’re talking to a snake and this is
a language that you don’t already know. You are going to make lots of mistakes. And the computer is going to seem
to judge your mistakes harshly. You will learn the word
“syntax error” a lot. And, if you’re like me, I think back to
the first time that I was programming. I was typing stuff on cards, and
you’d bring your card deck up and you’d hand it to the computer. And you’d read it through the computer. And then the computer would come back and
say syntax error. And sometimes it took several hours to
get back the results of your program. You’re going to get to do it in seconds,
but in the old days when I was young, it took hours sometimes. And then all you get back
is a syntax error and when I first started programming, I grew
to kind of hate the creature that lived inside the computer because I
thought that the creature didn’t like me. I thought the creature was
value judging my programs. I mean, I would write this thing and I
think it’s perfect and I would hand it in. And the computer would say, syntax error. And I’m like, huh? What’s up, syntax error. And then I would like, okay, I’ll make
my program better and here you go. And it would say syntax error again. And the thing that you’re going
to have to learn is that, syntax error doesn’t mean that
Python thinks you’re bad. It is not a judgement of your
ability as a programmer, it is not a judgement of your
potential to be a programmer. Syntax error means Python is lost. You are learning Python’s language
because Python can’t learn your language. You’re smarter than Python. We can teach you. You can learn, but Python can’t. And so when it says syntax error, even
though you feel like it’s a rejection, syntax error simply means
that Python is lost. It just doesn’t have really friendly
words when it says it’s lost, it just goes syntax error, which
literally is exactly what’s happening. Your syntax is not something
that Python understands. So just understand as you go through
the next couple of weeks that you will be frustrated. It’s not because you’re a bad person, it’s not because you’re never
going to figure it out. You will figure it out and
you will get it. And you have to sort of trust us as
we go through the first few weeks and learn the basics. And then as we connect
the basics together, then this thing will
make a lot more sense. I remember when I was first learning to
program, I would be like, lost, lost, lost, lost, lost, oh wow, I love this. And I expect that many of you will go
through that exact same feeling so you have to trust us. So up next, we’re going to actually talk
about the Python programming language.

Camera and you’re fine. Is it working? >> It’s working. >> Are you selfie-ing? >> Yeah, this is my selfie cam. My Gimble selfie cam. >> It works great. >> Yeah. So this way I can tape my
meeting of Allen Downey. >> Sweet. >> That’s gonna be sweet. >> Moments. >> The moment that I meet Allen. >> Palpable. >> It is.

Very cool indeed, I’d say. [LAUGH]
Folks. That’s Allen Downey, who started the whole
Think Java, Think Python revolution. Back in 1999, and
I’m going to meet him now the first time. >> You can ask him that question that I
should have asked him a long time ago. >> [SOUND] So what are your thoughts, Jeff, before
we meet the great Allen Downey? >> But you’ve met Alan before? >> I have. >> This is my first time. >> But it’s always exciting. >> Exactly. >> I’m Charles Severance. >> Charles, it’s great to see you. >> We’re co-authors. >> Yes?
We’ve never met in person. We talked on the phone. This is the famous Jeff Elkner, of course. >> Made famous by this guy. >> Well everybody got made famous. >> [LAUGH]
So the first question I was asking Jeff and he doesn’t even know the answer to
is why did you choose GFDL back in 1999? That was before Creative Commons,
before OCW, before everything. What possessed you? >> You know,
actually the first version of the book, I put it under the GNU Free
GFDL. >> Not not-
GFDL. The GPL.
Oh, you did the GPL. >> Because I didn’t even
know about the GFTL. >> And then somebody got ahold of you,
from MIT. >> And they said wait
a minute, this is documentation,
this is not code. You should use this other license,
and so I switched. And then when Creative Commons came along,
some of those licenses has been useful. Actually part of the reason that working
with O’Reilly has worked out very well. I do things usually under a non-commercial
Creative Commons license, and then that’s kind of a compromise. >> Yeah.
So it’s not ideal. >> But those are the details, so why
Though the non-commmercial’s I think a beautiful thing. Actually Creative Commons is thinking
about getting rid of it. [INAUDIBLE] Yeah. >> And I’m sad about that, because I
think it is a fine middle ground. E-copies can delivered free and
no one feels bad about that. Print copies you make money off of. So it’s pretty cool. >> I agree I think there’s
a nice use case for it. >> So have you ever tried to count
the number of derivative books of Think Python? >> No.
Do you think it’s 100? 200? 300? >> I don’t think. >> How to Think Like a Computer
Scientist Java version. >> If you go all the way back. >> There are a number of English language books that are modified versions. >> Including mine. >> There are translations into >> I count those as separate ones. >> Yep.
But like Runestone, like Brad Miller’s stuff,
Active more, I guess. >> Do you have an interactive version? >> No no I just have the Python for
Informatics print and e-version. >> Yeah, that’s
I did that many years ago, and then I fought with Cambridge Press. Remember that? >> Yes.
Remember those calls? Yeah.
So, but that’s, but like why did you give it away? I mean, it wasn’t so
cool in 1999 just to give books away. It was not normal. >> True.
No. But that’s the question that I wanted. >> Can we pause? I do want to,
I want to finish signing books >> So we have to talk later. >> Okay, we’ll get back to this. >> [LAUGH]

Hello, and welcome to by far the largest office hours
that we’ve ever had. We are in India and Bengaluru. And it is the IT capital of India and it has the greatest
weather of India. So I’ve had a wonderful time, and we met a bunch of students, and we don’t have time
for you to meet each one, so we’ll just walk
around and you can see just how many
people are here. So, here we go. So we will start like
on a really big shot. So we see that we have
a giant room full of people. And now let’s walk
around and everybody can sort of wave and say hi? Hello. Hi. Here we go. Make sure
we see everybody, hi. Here we go. Things are
working pretty good. Not so bad. We could do better. Hello world. Hello. Hello, oh hashtag!
Very well done. Hashtag. So we have our blind contingent
here at the front, of the blind programmers. Hello. So coming down this way. Hello. Hi. Cheers to Coursera. Cheers for Coursera. Hello. Hi. Yeah, here we go. Hi. That’s right, there we go. Okay, so there we go. An amazing turnout,
an amazing week, an amazing day and then
off to Mumbai we go. Oh, I should point to myself. So, we’ve had a wonderful
time here in Bengaluru and looking forward to seeing students in Mumbai
later this week. Cheers.