How to send "authority" header ?

[findo]

new_stream function in SimpleClient already defines authority header, so how to use self-defined authority ?

 let mut headers: Vec<Header> = vec![
            (b":method".to_vec(), method.to_vec()),
            (b":path".to_vec(), path.to_vec()),
            (b":authority".to_vec(), self.host.clone()),
            (b":scheme".to_vec(), self.conn.scheme().as_bytes().to_vec()),
        ];

eg. get function provides extra_headers, can we put authority header here ?

pub fn get(&mut self, path: &[u8], extra_headers: &[Header])
            -> HttpResult<Response> {
        let stream_id = try!(self.request(b"GET", path, extra_headers, None));
        self.get_response(stream_id)
    }