pushStack x = modify (\(PegState s a w n c b p) -> PegState (x:s) a w n c b p)
pushStack x = modify (\(PegState s a w n c b p) -> PegState (x:s) a w n c b p)
pushStack x = modify (\(PegState s a w n c b p) -> PegState (x:s) a w n c b p)