mathExpr :: Parser Expr
mathExpr = try binOp
        <|> try num
        <|> try antiQuote
        <|> labelref
mathExpr :: Parser Expr
mathExpr = try binOp
        <|> try num
        <|> try antiQuote
        <|> labelref
mathExpr = try binOp
        <|> try num
        <|> try antiQuote
        <|> labelref