Returning by-reference is useful when you want to use a function
to find which variable a reference should be bound to. When
returning references, use this syntax:
In this example, the property of the object returned by the
find_var function would be set, not the
copy, as it would be without using reference syntax.
Note:
Unlike parameter passing, here you have to use
& in both places - to indicate that you
return by-reference, not a copy as usual, and to indicate that
reference binding, rather than usual assignment, should be done
for $foo.
