You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lib.rs
    path of file: ./repos/tikv/components/api_version/src
    
    the code of the file until where you have to start completion: // Copyright 2021 TiKV Project Authors. Licensed under Apache-2.0.

#![feature(min_specialization)]
#![feature(associated_type_defaults)]

mod api_v1;
mod api_v1ttl;
pub mod api_v2;
pub mod keyspace;

use engine_traits::Result;
use kvproto::kvrpcpb::ApiVersion;
pub use match_template::match_template;
use txn_t
    
    fn test_parse_range() {
        assert_eq!(ApiV1::parse_range_mode((None, None)), KeyMode::Unknown);
        assert_eq!(
            ApiV1::parse_range_mode((Some(b"x"), None)),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV1Ttl::parse_range_mode((Some(b"m_a"), Some(b"na"))),
            KeyMode::Raw
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"t_a"), Some(b"t_z"))),
            KeyMode::Tidb
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"t"), Some(b"u"))),
            KeyMode::Tidb
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"m"), Some(b"n"))),
            KeyMode::Tidb
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"m_a"), Some(b"m_z"))),
            KeyMode::Tidb
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"x\0a"), Some(b"x\0z"))),
            KeyMode::Txn
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"x"), Some(b"y"))),
            KeyMode::Txn
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"r\0a"), Some(b"r\0z"))),
            KeyMode::Raw
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"r"), Some(b"s"))),
            KeyMode::Raw
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"t_a"), Some(b"ua"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"t"), None)),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((None, Some(b"t_z"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"m_a"), Some(b"na"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"m"), None)),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((None, Some(b"m_z"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"x\0a"), Some(b"ya"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"x"), None)),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((None, Some(b"x\0z"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"r\0a"), Some(b"sa"))),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((Some(b"r"), None)),
            KeyMode::Unknown
        );
        assert_eq!(
            ApiV2::parse_range_mode((None, Some(b"r\0z"))),
            KeyMode::Unknown
        );
    }