input: Write a python function to sum the values of a dictionary.
  assert sum_dict_values({'a': 4, 'b': 2, 'c': 1}) == 7
  assert sum_dict_values({'x': 10, 'y': 20, 'z': 30}) == 60
  assert sum_dict_values({'one': 1, 'two': 2, 'three': 3}) == 6
output: def sum_dict_values(d):
      return sum(d.values())