Noting xrange -> range in Python3

Fixes #31

control_flow.md

@@ -92,7 +92,7 @@ In this program, we are printing a *sequence* of numbers. We generate this seque
 
 What we do here is supply it two numbers and `range` returns a sequence of numbers starting from the first number and up to the second number. For example, `range(1,5)` gives the sequence `[1, 2, 3, 4]`. By default, `range` takes a step count of 1. If we supply a third number to `range`, then that becomes the step count. For example, `range(1,5,2)` gives `[1,3]`. Remember that the range extends *up to* the second number i.e. it does *not* include the second number.
 
-Note that `range()` generates a sequence of numbers all at once, so this is safe to use only for small ranges. If you want a long range but generated only one number at a time, then use `xrange()`. Lists are explained in the [data structures chapter](./data_structures.md#data-structures).
+Note that `range()` generates only one number at a time, if you want the full list of numbers, call `list()` on the `range()`, for example, `list(range(5))` will result in `[0, 1, 2, 3, 4]`. Lists are explained in the [data structures chapter](./data_structures.md#data-structures).
 
 The `for` loop then iterates over this range - `for i in range(1,5)` is equivalent to `for i in [1, 2, 3, 4]` which is like assigning each number (or object) in the sequence to i, one at a time, and then executing the block of statements for each value of `i`.  In this case, we just print the value in the block of statements.