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: utils.rs
    path of file: ./repos/dufs/src
    
    the code of the file until where you have to start completion: use anyhow::{anyhow, Context, Result};
use chrono::{DateTime, Utc};
#[cfg(feature = "tls")]
use rustls_pki_types::{CertificateDer, PrivateKeyDer};
use std::{
    borrow::Cow,
    path::Path,
    time::{Duration, SystemTime, UNIX_EPOCH},
};

pub fn unix_now() -> Result<Duration> {
    SystemTime::now()
        .duration_since
    
pub fn load_certs<T: AsRef<Path>>(filename: T) -> Result<Vec<CertificateDer<'static>>> {
    // Open certificate file.
    let cert_file = std::fs::File::open(filename.as_ref())
        .with_context(|| format!("Failed to access `{}`", filename.as_ref().display()))?;
    let mut reader = std::io::BufReader::new(cert_file);

    // Load and return certificate.
    let mut certs = vec![];
    for cert in rustls_pemfile::certs(&mut reader) {
        let cert = cert.with_context(|| "Failed to load certificate")?;
        certs.push(cert)
    }
    if certs.is_empty() {
        anyhow::bail!("No supported certificate in file");
    }
    Ok(certs)
}