def f(text, m, n): text = "{}{}{}".format(text, text[:m], text[n:]) result = "" for i in range(n, len(text)-m): result = text[i] + result return result assert f("abcdefgabc", 1, 2) == 'bagfedcacbagfedc'
assert f(??) == 'bagfedcacbagfedc'
assert f("abcdefgabc", 1, 2) == ??