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: memory.rs
    path of file: ./repos/artichoke/artichoke-backend/src/load_path
    
    the code of the file until where you have to start completion: use std::borrow::Cow;
use std::collections::hash_map::Entry as HashEntry;
use std::collections::{HashMap, HashSet};
use std::fmt;
use std::io;
use std::path::{Path, PathBuf};

use bstr:
    
    pub fn mark_required(&mut self, path: &Path) -> io::Result<()> {
        let path = absolutize_relative_to(path, &self.cwd);
        if path.strip_prefix(RUBY_LOAD_PATH).is_err() {
            let mut message = String::from("Only paths beginning with ");
            message.push_str(RUBY_LOAD_PATH);
            message.push_str(" are writable");
            return Err(io::Error::new(io::ErrorKind::PermissionDenied, message));
        }
        match normalize_slashes(path) {
            Ok(path) => {
                self.loaded_features.insert(path.into());
                Ok(())
            }
            Err(_) => Err(io::Error::new(io::ErrorKind::NotFound, ConvertBytesError::new())),
        }
    }