**Use case**

Like `date_time_input_format = 'best_effort'` but with disambiguation to American mm/dd/yyyy style.

{
            UTF8,
            ASCII,
        };
        Charset charset = Charset::UTF8;
    } pretty;
    struct
    {
        /**
         * Some buffers (kafka / rabbit) split the rows internally using callback,
         * and always send one row per message, so we can push there formats
         * without framing / delimiters (like ProtobufSingle). In other cases,
         * we have to enforce exporting at most one row in the format output,
         * because Protobuf without delimiters is not generally useful.
         */
        bool allow_multiple_rows_without_delimiter = false;
    } protobuf;
    struct
    {
        uint32_t client_capabilities = 0;
        size_t max_packet_size = 0;
        uint8_t * sequence_id = nullptr; 
    } mysql_wire;
    struct
    {
        std::string regexp;