input: Write a python function to clear all items from a dictionary.
  assert clear_dict({'a':1, 'b':2, 'c':3}) == {}
  assert clear_dict({'x':10, 'y':20, 'z':30}) == {}
  assert clear_dict({'key1': 'value1', 'key2': 'value2'}) == {}
output: def clear_dict(d):
      d.clear()
      return d