presto-main/src/main/java/io/prestosql/operator/scalar/Re2JRegexpFunctions.java/Re2JRegexpFunctions/regexpExtract
class Re2JRegexpFunctions:    @SqlNullable
    @Description("returns regex group of extracted string with a pattern")
    @ScalarFunction
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice regexpExtract(@SqlType("varchar(x)") Slice source, @SqlType(Re2JRegexpType.NAME) Re2JRegexp pattern, @SqlType(StandardTypes.BIGINT) long groupIndex)
    {
        return pattern.extract(source, groupIndex);
    }