h :: IO ()
h = do print 'a'
       rec print 'b'
           print 'c'
       print 'd'
h :: IO ()
h = do print 'a'
       rec print 'b'
           print 'c'
       print 'd'
h = do print 'a'
       rec print 'b'
           print 'c'
       print 'd'