specify another serial number for a enum enum_id - id of enum idx - new serial number. If another enum with the same serial number exists, then all enums with serial numbers >= the specified idx get their serial numbers incremented (in other words, the new enum is put in the middle of the list of enums). If idx >= get_enum_qty() then the enum is moved to the end of the list of enums. returns: comment stringsuccess set_enum_idx(long enum_id, long idx);