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: mod.rs
    path of file: ./repos/wrangler-legacy/src/commands/dev/tls
    
    the code of the file until where you have to start completion: mod certs;
pub use certs::generate_cert;

use anyhow::Result;
use core::task::{Context, Poll};
use fs
    
fn load_certs(file: PathBuf) -> io::Result<Vec<rustls::Certificate>> {
    // Open certificate file.
    let certfile = get_tls_file(file)?;
    let mut reader = io::BufReader::new(certfile);

    // Load and return certificate.
    match rustls_pemfile::certs(&mut reader) {
        Ok(certs) => Ok(certs.into_iter().map(rustls::Certificate).collect()),
        Err(_) => Err(io_error("failed to load certificate".into())),
    }
}