input: Write a function to sort a list of tuples by the second element using a lambda function.
  assert sort_list([(3, 4), (5, 6), (1, 2)]) == [(1, 2), (3, 4), (5, 6)]
  assert sort_list([(10, 1), (9, 5), (2, 3)]) == [(10, 1), (2, 3), (9, 5)]
  assert sort_list([(7, 7), (4, 3), (6, 8)]) == [(4, 3), (7, 7), (6, 8)]
output: def sort_list(lst):
      return sorted(lst, key=lambda x: x[1])