Function twrs_sms::is_delivered

pub fn is_delivered<'r>(
    response: &mut Response, 
    account_sid: &str, 
    auth_token: &str
) -> Result<&'r str, TWRSError>

This will check if the status is set to delivered within the Twilio API Within this function is a while loop that breaks on the API returning anything other than delivered, if the response is not delivered this will return TWRSError::NotDelivered