showShunt :: Token a => Shunt a -> String
showShunt (S ts ss os ru) =
  pad 20 ts ++ pad' 20 ss ++ pads 20 os ++ "   " ++ showRule ru
showShunt :: Token a => Shunt a -> String
showShunt (S ts ss os ru) =
  pad 20 ts ++ pad' 20 ss ++ pads 20 os ++ "   " ++ showRule ru
showShunt (S ts ss os ru) =
  pad 20 ts ++ pad' 20 ss ++ pads 20 os ++ "   " ++ showRule ru