Clarify calling functions

lindboe · lindboe · commit eda827bb2ac8 · 2020-01-24T15:00:25.000-08:00
The original explanation says that we re-write the name of the example
function at the bottom of the file "because Python reads the file from
top to bottom, so we need to re-write the name of the function." I find
that explanation a bit confusing myself.

I think two things were conflated here:
1) The difference between defining and running a function
2) Explaining that Python reads files from top to bottom, and needs
functions to be defined before they can be called

I tried to more explicitly explain that what we're doing is calling a
function we just defined, and break these concepts apart more.
diff --git a/en/python_introduction/README.md b/en/python_introduction/README.md
@@ -815,7 +815,7 @@ hi()
 
 Okay, our first function is ready!
 
-You may wonder why we've written the name of the function at the bottom of the file. This is because Python reads the file and executes it from top to bottom. So in order to use our function, we have to re-write it at the bottom.
+You may wonder why we've written the name of the function at the bottom of the file. When we write `def hi():` and the indented lines following, this is us writing instructions for what the `hi()` function should do. Python will read and remember these instructions, but won't run the function yet. To tell Python we want to run the function, we have to call the function with `hi()`. Python reads the file and executes it from top to bottom, so we have to define functions in the file before we call them.
 
 Let's run this now and see what happens:
 
