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: testing.rs
    path of file: ./repos/crates.io/crates/crates_io_index
    
    the code of the file until where you have to start completion: use anyhow::anyhow;
use git2::{ErrorCode, Repository, Sort};
use std::path::Path;
use std::sync::Mutex;
use std::thread;
use te
    
    pub fn crate_exists(&self, crate_name: &str) -> anyhow::Result<bool> {
        let repo = self.repository.lock().unwrap();

        let path = crate::Repository::relative_index_file(crate_name);

        let head = repo.head()?;
        let tree = head.peel_to_tree()?;

        match tree.get_path(&path) {
            Ok(_) => Ok(true),
            Err(error) if error.code() == ErrorCode::NotFound => Ok(false),
            Err(error) => Err(error.into()),
        }
    }