0xFF69B4

  # milk_cows :: Person -> Tired Person
  def milk_cows(person):
    ...
    person["tired"] = True
    return person

  # feed_pigs :: Person -> Tired Person
  def feed_pigs(person):
    ...
    person["tired"] = True
    return person

  # birthday :: Person -> Person
  def birthday(person):
    person["age"] += 1
    return person

  # willy :: Person
  willy = {"age": 32, "tired": False}

  # fmap and >>=
  print(milk_cows(birthday(feed_pigs(willy))))