input: Write a python function to sort a list of tuples based on the third element in each tuple.
  assert sort_tuple_list([(21, "ABC", 33), (9, "XYZ", 88), (67, "MNO", 37)]) == [(21, "ABC", 33), (67, "MNO", 37), (9, "XYZ", 88)]
  assert sort_tuple_list([(5, "Z", 10), (3, "Y", 5), (9, "X", 15)]) == [(3, "Y", 5), (5, "Z", 10), (9, "X", 15)]
  assert sort_tuple_list([(1, "A", 1), (4, "B", 4), (2, "C", 2)]) == [(1, "A", 1), (2, "C", 2), (4, "B", 4)]
output: def sort_tuple_list(lst):
      return sorted(lst, key=lambda x: x[2])