Implement 'list-sort' in Scheme

[Katie Burke]

list-sort should return a list containing the elements of list sorted according to the predicate. ( http://www.scheme.com/tspl4/objects.html#./objects:s62 ).

(list-sort < '(3 4 2 1 2 5))

Traceback (most recent call last):
File "stdin", line 1, col 2
RunTimeError: unbound variable 'list-sort'