input: Write a python function to sort a list that contains both numbers and strings, ordering them by their string representation.
  assert sort_mixed_list([1, 'c', 3, 'a', 2, 'b']) == [1, 'a', 2, 'b', 3, 'c']
  assert sort_mixed_list([10, 'z', '2', 3, 'a']) == [10, '2', 3, 'a', 'z']
  assert sort_mixed_list(['apple', 5, 'banana', 1, 'carrot']) == [1, 5, 'apple', 'banana', 'carrot']
output: def sort_mixed_list(mixed_list):
      return sorted(mixed_list, key=str)