fn subpath<T: AsRef<str>>(path: T) -> String
fn gen_list(manga_list: &[&str]) -> Result<Vec<String>>
fn start_dl(manga_list: &[&str], sender: SyncSender<Page>) -> Result<()>
fn dl_chapter(dir: &str, link: &str, sender: &SyncSender<Page>) -> Result<()>