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The best way to learn programming is to first think of a program and then figure out how to create it. This course will help you learn in this way. However, there are a few core tools that will be used in nearly all the programs you write. This section will teach you those tools.

There are many commands available to you in Python. These commands are called “functions.” The print function displays a message to the user (it “prints” the message to your screen). You can use it like this:

>>> print("hello world")
hello world

Using a function like this is called “calling” a function. You call a function by adding parentheses at the end. You can give information to the function by putting things inside the parentheses. Each piece of information we give to the function is called an “argument.” Above, we passed only one argument (a line of text) to print.

When you pass text as an argument, make sure you put quotes around the words. If you don’t, you’ll get an error. You don’t need to put quotes around numbers, though.

>>> print(hello)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'hello' is not defined
>>> print("hello")
>>> print(3)

You can use either double or single quotes; it doesn’t matter:

>>> print("hello there")
hello there
>>> print('hello there')
hello there

We can pass multiple arguments to a function by separating the arguments with commas, like this:

>>> print("one", 2, "three")
one 2 three


When you see Python shell examples like the ones above, try typing similar commands on your own. Often, things will not make sense until you do it yourself.

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