demo_pair_Functor = do
  print (fmap id (Pair 2 3))
  print (((fmap (*3)) . (fmap (*5))) (Pair 1 2))
  print (fmap ((*3) . (*5)) (Pair 1 2))
demo_pair_Functor = do
  print (fmap id (Pair 2 3))
  print (((fmap (*3)) . (fmap (*5))) (Pair 1 2))
  print (fmap ((*3) . (*5)) (Pair 1 2))
demo_pair_Functor = do
  print (fmap id (Pair 2 3))
  print (((fmap (*3)) . (fmap (*5))) (Pair 1 2))
  print (fmap ((*3) . (*5)) (Pair 1 2))