input: Write a python function to find common words in two lists.
  assert common_words(['John', 'Paul', 'George', 'Ringo'], ['George', 'Ringo', 'John']) == ['John', 'George', 'Ringo']
  assert common_words(['apple', 'banana', 'cherry'], ['banana', 'cherry', 'date', 'fig']) == ['banana', 'cherry']
  assert common_words(['dog', 'cat', 'mouse'], ['elephant', 'dog', 'mouse', 'tiger']) == ['dog', 'mouse']
output: def common_words(list1, list2):
      return sorted(list(set(list1) & set(list2)))