input: Write a python function to check if a dictionary has all unique values.
  assert check_unique_values({'alec': 'alec', 'bob': 'bob', 'sara': 'sara', 'john': 'john', 'elon': 'elon'}) == True
  assert check_unique_values({'a': 'apple', 'b': 'banana', 'c': 'apple'}) == False
  assert check_unique_values({'x': 'x-ray', 'y': 'yoyo', 'z': 'zebra'}) == True
output: def check_unique_values(d):
      return len(d.values()) == len(set(d.values()))