input: Write a python function to sum the values of a dictionary.
  assert sum_values({"a": 1, "b": 2, "c": 3}) == 6
  assert sum_values({"x": 10, "y": 20, "z": 30}) == 60
  assert sum_values({"key1": 100, "key2": 200}) == 300
output: def sum_values(d):
      return sum(d.values())