presto-main/src/main/java/io/prestosql/operator/scalar/MathFunctions.java/MathFunctions/signInteger
class MathFunctions:    @Description("signum")
    @ScalarFunction("sign")
    @SqlType(StandardTypes.INTEGER)
    public static long signInteger(@SqlType(StandardTypes.INTEGER) long num)
    {
        return (long) Math.signum(num);
    }