input: Write a python function to invert a dictionary.
  assert invert_dictionary({"apple": 3, "banana": 4, "carrot": 2}) == {3: 'apple', 4: 'banana', 2: 'carrot'}
  assert invert_dictionary({"one": 1, "two": 2, "three": 3}) == {1: 'one', 2: 'two', 3: 'three'}
  assert invert_dictionary({"x": 10, "y": 20, "z": 30}) == {10: 'x', 20: 'y', 30: 'z'}
output: def invert_dictionary(d):
      return {v: k for k, v in d.items()}