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And to start with Python,
first start the Python shell.

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So if you don't know how to start it,
please go back to the introduction section

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where you can see the
lesson on how to install

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Python on Windows,
on Linux, and on Mac OS.

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And then come back
here for the explanations.

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So this is the Python
shell, and the first thing you

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can see here is the Python
version you have here.

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So I have version 3, Python 3.9,

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but just the important thing is
that you have Python 3, okay?

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And then you are going to see here
three brackets, three angle brackets,

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and that's where you are going
to type some Python instructions.

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So we will see later that you can create
complete files with lots of lines of code,

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which are basically all instructions
that are going to be executed.

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And with the Python shell instead,
you don't write a complete file,

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you just write one instruction at
a time, and when you press enter,

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the instruction is going
to be executed, and in

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addition to that, the
result of the instruction

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will also be evaluated and
printed directly on the shell.

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So let's just type anything.

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Let's just type number 3.

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I am going to press enter, and
you can see now I have 3 here.

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So that was the instruction,
which is just a number for now,

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so it doesn't do
anything, but you can see

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we have the instruction,
which is evaluated.

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So of course, 3 is evaluated
to 3, and it's printed here.

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I can also do "Hello World" like this.

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So use double quotes for now.

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Okay, "Hello World", I press
enter, and you can see "Hello World".

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So here you have your first
"Hello World" program in Python.

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And in this section, we
are going to continue with

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this Python shell to
discover variables, et cetera.

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And so you can just
type literal value like this,

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and you can also, for
example, use Python functions.

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So there is one Python function,
which is named len for length,

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and you have to open and close
parentheses and need to give,

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for example, a string of
characters like this or a list.

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So if I just type "Hello World"
like this, here I press enter,

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and this, as you can see, this gives
us 11, because this Python function,

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which is in the core module,
in the core Python module,

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is going to compute the length
of the string here, which is 11.

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So we have 11 characters,
including the space.

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Okay, and don't worry about this.

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We are going to come
back to that just later.

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Here it will just show you what
you can do with the Python shell.

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So you can write instructions.

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You press enter, okay, you can
press enter, as you can see here.

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I press enter, and whatever is here

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will be executed and also
evaluated and printed here.