presto-main/src/main/java/io/prestosql/operator/scalar/JoniRegexpFunctions.java/JoniRegexpFunctions/regexpExtract
class JoniRegexpFunctions:    @SqlNullable
    @Description("string extracted using the given pattern")
    @ScalarFunction
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice regexpExtract(@SqlType("varchar(x)") Slice source, @SqlType(JoniRegexpType.NAME) Regex pattern)
    {
        return regexpExtract(source, pattern, 0);
    }