number :: TokenParser Int
number = token go P.<?> "number"
  where go (Number n) = Just n
        go _          = Nothing
number :: TokenParser Int
number = token go P.<?> "number"
  where go (Number n) = Just n
        go _          = Nothing
number = token go P.<?> "number"
  where go (Number n) = Just n
        go _          = Nothing