def append(xs, ys):
    result = []
    for element in xs:
        result.append(element)
    for element in ys:
        result.append(element)
    return result


def concat(lists):
    pass


def filter_clone(function, xs):
    pass


def length(xs):
    pass


def map_clone(function, xs):
    pass


def foldl(function, xs, acc):
    pass


def foldr(function, xs, acc):
    pass


def reverse(xs):
    pass

@@ -78,25 +78,70 @@
 end(element)
+ # Not sure if using .append here is cheating
 %0A
-
     for elem
@@ -217,36 +217,116 @@
 cat(lists):%0A    
-pass
+result = %5B%5D%0A    for l in lists:%0A        result = append(result, l)%0A    return result
 %0A%0A%0Adef filter_cl

Implement concat