mulop   =   do{ symbol "*"; return $ BinopExpr MulOp }
        <|> do{ symbol "/"; return $ BinopExpr DivOp }
mulop   =   do{ symbol "*"; return $ BinopExpr MulOp }
        <|> do{ symbol "/"; return $ BinopExpr DivOp }
mulop   =   do{ symbol "*"; return $ BinopExpr MulOp }
        <|> do{ symbol "/"; return $ BinopExpr DivOp }