1.
a.
Say we type the following:
>>> x = [1, 2, 3]
>>> y = [4, 5, 6]
>>> list_swap1(x, y)

If we look at what's going on in memory when the function is first called:

x  ---->  [1, 2, 3]
y --------------> [4, 5, 6]
            ^        ^
list_swap1: |        |
a ----------|        |
b -------------------|

There are two list objects and x and y reference them.  When the function is called,
a and b then also reference the same lists respectively.

In the program, changing the values of a and b will NOT change what the outer variables
x and y reference.

b.  This is another attempt at it, but when the function is called the picture above
will be the same.  This time, we do full copies of a and b using the slicing operation,
however, this still will NOT change the outer variables.

c. This is almost there.  Now, instead of changing the values of a and b, we are
mutating/changing the list themselves.  This will swap SOME of the values, however,
if a and b have different lengths then either an exception will occur or only
some of the data will get swapped.