gistfile1.txt

    let mut req = self.client
        .post(&addr)
        .header(Connection::close())
        .header(ContentType::json())
        .header(Authorization(Bearer { token: String::from(self.token) }));

    if let &mut Some(ref c) = context {
        let s: String = match serde_json::to_string(c) {
            Ok(r) => r,
            Err(_) => return Converse::Result::Error("serde_json::to_string(context) failed."),
        };
        req = req.body(&s);
    };