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: key_types.rs
    path of file: ./repos/incubator-teaclave/common/rusty_leveldb_sgx/src
    
    the code of the file until where you have to start completion: use crate::cmp::Cmp;
use crate::types::SequenceNumber;

use std::cmp::Ordering;
use std::io::Write;

use integer_encoding::{FixedInt, FixedIntWriter, VarInt, VarIntWriter};

// The following typedefs are used to distinguish between the different key formats used internally
// by different modules.

// TODO: At some point,
    
    pub fn new_full(k: UserKey, s: SequenceNumber, t: ValueType) -> LookupKey {
        let mut key = Vec::new();
        let internal_keylen = k.len() + U64_SPACE;
        key.resize(k.len() + internal_keylen.required_space() + U64_SPACE, 0);

        {
            let mut writer = key.as_mut_slice();
            writer
                .write_varint(internal_keylen)
                .expect("write to slice failed");
            writer.write_all(k).expect("write to slice failed");
            writer
                .write_fixedint(s << 8 | t as u64)
                .expect("write to slice failed");
        }

        LookupKey {
            key,
            key_offset: internal_keylen.required_space(),
        }
    }