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: shell_history.rs
    path of file: ./repos/mcfly/src
    
    the code of the file until where you have to start completion: use crate::settings::HistoryFormat;
use regex::Regex;
use std::env;
use std::fmt;
use std::fs;
use std::fs::File;
use std::fs::OpenOptions;
use std::io::Read;
use std::io::Write;
use std::path::Path;
use std::path::PathBuf;
use std::str::FromStr;
use std::time::{SystemTime, UNIX_EPOCH};

fn read_ignoring_utf_errors(path: &Path) -> String {
    let mut f =
        File::open(path).
    
pub fn append_history_entry(command: &HistoryCommand, path: &Path, debug: bool) {
    let mut file = OpenOptions::new()
        .write(true)
        .append(true)
        .open(path)
        .unwrap_or_else(|err| {
            panic!(
                "McFly error: please make sure the specified --append-to-histfile file ({:?}) exists ({})",
                path, err
            )
        });

    if debug {
        println!("McFly: Appended to file '{:?}': {}", &path, command);
    }

    if let Err(e) = writeln!(file, "{}", command) {
        eprintln!("Couldn't append to file '{}': {}", path.display(), e);
    }
}