titles to using-functions

Akuli · Akuli · commit edb4756ed0fb · 2016-11-11T23:57:30.000+02:00
diff --git a/lists-and-tuples.md b/lists-and-tuples.md
@@ -145,7 +145,7 @@ None
 ```
 
 This is the same thing that happened way back when [we assigned
-print's return value to a variable](using-functions.md).
+print's return value to a variable](using-functions.md#return-values).
 
 ## What is what?
 
diff --git a/using-functions.md b/using-functions.md
@@ -29,20 +29,31 @@ Hello World!
 
 But what exactly is print?
 
+## What are functions?
+
+Let's see what happens if we type `print` without the `('Hello')` part.
+
 ```py
 >>> print
 <built-in function print>
 >>> 
 ```
 
-In Python 3, print is a function. Functions do something when they are
+We could also type `print(print)`, it would do the same thing. Python
+replied to us with some information about print wrapped in `<>`.
+
+As we can see, print is a function. Functions do something when they are
 **called** by typing their name and parentheses. Inside the
 parentheses, we can pass some arguments too. In `print("hello")` the
 function is `print` and we give it one argument, which is `"hello"`.
 
-Functions are sometimes thoght of as difficult to understand, but they
-really are not. They just do something when they are called. But if we
-do `x = print('hello')`, what is x?
+Functions are easy to understand, They simply **do something when they
+are called**. Functions run immediately when we call them, so the
+text appears on the screen right away when we run `print(something)`.
+
+## Return values
+
+If we do `x = print('hello')`, what is x?
 
 ```py
 >>> x = print('hello')
@@ -58,8 +69,7 @@ explained in more detail:
 - In `x = print('hello')`, the right side is processed first.
 - `print('hello')` calls the print function with the argument
     `'hello'`.
-- The function runs **immediately** when it's called. It shows the word
-    hello.
+- The function runs. It shows the word hello.
 - The print function **returns** None. All functions need to return
     something, and print returns None because there's no need to return
     anything else.
@@ -68,17 +78,46 @@ explained in more detail:
     there, and the assignment now looks like `x = None`.
 - x is now None.
 
+Now we understand what a return value is. When we call the function,
+Python "replaces" `function(args)` with whatever the function returns.
+
 Calling a function without assigning the return value to anything (e.g.
 `print('hello')` instead of `x = print('hello')`) simply throws away
-the return value. The interactive `>>>` prompt also echoes the return
-value back if it's not None.
+the return value. The interactive `>>>` prompt doesn't echo the return
+value back because it's None.
 
 Of course, `x = print('hello')` is useless compared to `print('hello')`
 because the print function always returns None and we can do `x = None`
 without any printing.
 
+Not all functions return None. The input function can be used for
+getting a string from the user.
+
+```py
+>>> x = input("Enter something:")
+Enter something:hello
+>>> x
+'hello'
+>>> 
+```
+
+`input("Enter something:")` showed the text `Enter something:` on the
+screen and waited for me to type something. I typed hello and pressed
+Enter. Then input returned the hello I typed as a string and it was
+assigned to x.
+
+Usually we want to add a space after the `:`, like this:
+
+```py
+>>> x = input("Enter something: ")  # now there's space between : and where i type
+Enter something: hello
+>>> 
+```
+
+## More about print
+
 We can also print an empty line by calling print without any
-arguments:
+arguments.
 
 ```py
 >>> print()
@@ -97,7 +136,7 @@ world
 ```
 
 If we want to print a backslash, we need to **escape** it by typing
-two backslashes:
+two backslashes.
 
 [comment]: # (For some reason, GitHub's syntax highlighting doesn't)
 [comment]: # (work here.)
@@ -123,37 +162,14 @@ Unlike with `+`, the arguments don't need to be strings.
 >>> 
 ```
 
-Not all functions return None. The input function can be used for
-getting a string from the user.
-
-```py
->>> x = input("Enter something:")
-Enter something:hello
->>> x
-'hello'
->>> 
-```
-
-`input("Enter something:")` showed the text `Enter something:` on the
-screen and waited for me to type something. I typed hello and pressed
-Enter. Then input returned the hello I typed as a string and it was
-assigned to x.
-
-Usually we want to add a space after the `:`, like this:
-
-```py
->>> x = input("Enter something: ")  # now there's space between : and where i type
-Enter something: hello
->>> 
-```
-
 ## Summary
 
 - `function()` calls a function without any arguments, and
     `function(1, 2, 3)` calls a function with 1, 2 and 3 as arguments.
-    `x = function()` calls a function, and assigns the return value of
-    the call to x.
 - When a function is called, it does something and returns something.
+- `function(stuff)` is "replaced" with the return value in the code
+    that called it. For example, `x = function()` calls a function, and
+    then does `x = the_return_value` and the return value ends up in x.
 - Python comes with `print` and `input`. They are built-in functions.
 
 ***
