code: def host(self) -> str:
          
          host = self._message.headers.get(hdrs.HOST)
          if host is not None:
              return host
          else:
              return socket.getfqdn()
docs: Hostname of the request.
  
          Hostname is resolved in this order:
  
          - overridden value by .clone(host=new_host) call.
          - HOST HTTP header
          - socket.getfqdn() value