The benefit of ordering the elements in a list array is that
we can easily grab one value out of the list on demand.
To do this, we use Perl's subscripting operator using the
format:
$array_name[list_element_number]
When pulling an element out of a list array, we create a
scalar variable with the same name as the array, prefixed
with the usual dollar sign that denotes scalar variables.
For example, the first element of the array
@available_colors is accessed as $available_colors[0].
Notice that the first element is accessed with a zero. This
is important. List arrays begin counting at zero, not one.
Thus, $available_colors[0] is a variable placeholder for
the word "red". Likewise, $available_colors[1] equals
"green" and $available_colors[2] equals "blue".
