Function file_answers 

pub fn file_answers(
    root: &Path,
    address: &MailAddress,
    name: &str,
    mail: &TranscriptMail,
) -> Result<usize>

File every answer the session at address gave its user that is not filed yet, in the user’s mailbox under root, from the session (name is what the user knows it by). Returns how many were filed now.