presto-main/src/main/java/io/prestosql/operator/scalar/MathFunctions.java/MathFunctions/absTinyint
class MathFunctions:    @Description("absolute value")
    @ScalarFunction("abs")
    @SqlType(StandardTypes.TINYINT)
    public static long absTinyint(@SqlType(StandardTypes.TINYINT) long num)
    {
        checkCondition(num != Byte.MIN_VALUE, NUMERIC_VALUE_OUT_OF_RANGE, "Value -128 is out of range for abs(tinyint)");
        return Math.abs(num);
    }