def test_combine_lists(self):
u = ['a', 'b', 'c']
v = ['1', '2', '3']
w = ['a', '1', 'b', '2', 'c', '3']
self.assertListEqual(w, Question_2.combine_lists(u, v))
def sign_sequence_to_expression(seq):
signs = ['+'] + list(seq)
digits = map(str, range(1, len(seq) + 2))
expression = ''.join(Question_2.combine_lists(signs, digits))
return expression
