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: reader.rs
    path of file: ./repos/el_monitorro/src/sync
    
    the code of the file until where you have to start completion: use self::atom::AtomReader;
use self::json::JsonReader;
use self::rss::RssReader;
use crate::http_client;
use chrono::DateTime;
use chrono::Utc;
use isahc::Request;
use std::io;

pub mod atom;
pub mod json;
pub mod rss;

#[derive(Debug)]
pub struct FeedReaderError {
    
    
pub fn validate_rss_url(url: &str) -> Result<String, FeedReaderError> {
    let data = read_url(url)?;

    let rss_reader = RssReader {
        url: url.to_string(),
    };

    if rss_reader.read_from_bytes(&data).is_ok() {
        return Ok("rss".to_string());
    }

    let atom_reader = AtomReader {
        url: url.to_string(),
    };

    if atom_reader.read_from_bytes(&data).is_ok() {
        return Ok("atom".to_string());
    }

    let json_reader = JsonReader {
        url: url.to_string(),
    };

    if json_reader.read_from_bytes(&data).is_ok() {
        return Ok("json".to_string());
    }

    Err(FeedReaderError {
        msg: "Url is not a feed".to_string(),
    })
}