presto-main/src/main/java/io/prestosql/operator/scalar/StringFunctions.java/StringFunctions/reverse
class StringFunctions:    @Description("reverse all code points in a given string")
    @ScalarFunction
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice reverse(@SqlType("varchar(x)") Slice slice)
    {
        return SliceUtf8.reverse(slice);
    }