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/dystopia/dytp-protocol/src
    
    the code of the file until where you have to start completion: pub mod delim;
pub mod method;
pub mod raw;
pub mod size;

use crate::raw::Raw;
use crate::size::Size;
use bytes::BytesMut;
//
// +------------------------------------------------------+
// |[4 bytes: raw payload size] 
    
pub fn parse(buf: &mut BytesMut) -> Option<Protocol> {
    let size = if buf.len() >= 4 {
        Size::parse(&buf as &[u8])
    } else {
        return None;
    };

    let raw = if buf.len() - 4 >= size.0 as usize {
        let mut raw = buf.split_to(size.0 as usize + 4);
        raw.split_to(4);
        Raw::wrap(raw)
    } else {
        return None;
    };

    Some(Protocol(size, raw))
}