operator :: Parser String
operator = lexeme $ do
    op <- oneOf "+-*/><%"
    end <- case op of
        '>' -> option "" (try (string ">"))
        '<' -> option "" (try (string "<"))
        _ -> return ""
    return $ op:end
operator :: Parser String
operator = lexeme $ do
    op <- oneOf "+-*/><%"
    end <- case op of
        '>' -> option "" (try (string ">"))
        '<' -> option "" (try (string "<"))
        _ -> return ""
    return $ op:end
operator = lexeme $ do
    op <- oneOf "+-*/><%"
    end <- case op of
        '>' -> option "" (try (string ">"))
        '<' -> option "" (try (string "<"))
        _ -> return ""
    return $ op:end