def test_1(self): Test.assert_equals(sorted(permutations('a')), ['a'])
def test_2(self): Test.assert_equals(sorted(permutations('ab')), ['ab', 'ba'])
def test_3(self): Test.assert_equals(sorted(permutations('aabb')), ['aabb', 'abab', 'abba', 'baab', 'baba', 'bbaa'])