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/Theseus/kernel/ota_update_client/src
    
    the code of the file until where you have to start completion: //! Functions to communicate with a network server that provides over-the-air live update functionality.
//! 

#![no_std]
#![feature(slice_concat_ext)]

#[macro_use] extern crate log;
#[macro_use] extern crate alloc;
extern crate spawn;
extern crate task;
extern crate sha3;
extern crate percent_encoding;
extern crate http_client;
extern crate itertools;
extern crate time;
extern crate net;

use core::str;
use alloc::{
    vec::Vec,
    collections::BTreeSet,
    string::{String, ToString},
    sync::Arc,
};
use itertools::Itertools;
use sha3::{Digest, Sha3_512};
use percent_encoding::{DEFAULT_ENCODE_SET, utf8_percent_encode};
use http_client::{HttpResponse, HttpClient, check_http_request};
use time::{Duration, Ins
    
pub fn parse_diff_lines(diffs: &Vec<String>) -> Result<Diff, &'static str> {
    let mut pairs: Vec<(String, String)> = Vec::with_capacity(diffs.len());
    let mut state_transfer_functions: Vec<String> = Vec::new();
    for diff in diffs {
        // addition of new crate
        if diff.starts_with('+') {
            pairs.push((
                String::new(), 
                diff.get(1..).ok_or("error parsing (+) diff line")?.trim().to_string(),
            ));
        } 
        // removal of old crate
        else if diff.starts_with('-') {
            pairs.push((
                diff.get(1..).ok_or("error parsing (-) diff line")?.trim().to_string(), 
                String::new()
            ));
        }
        // replacement of old crate with new crate
        else if let Some((old, new)) = diff.split("->").collect_tuple() {
            pairs.push((old.trim().to_string(), new.trim().to_string()));
        }
        // state transfer function
        else if diff.starts_with('@') {
            state_transfer_functions.push(
                diff.get(1..).ok_or("error parsing (@state_transfer) diff line")?.trim().to_string(),
            )
        }
        else {
            error!("parse_diff_lines(): error parsing diff line: {:?}", diff);
            return Err("error parsing diff line");
        }
    }

    Ok(Diff { pairs, state_transfer_functions })
}