docs: async def _init(self):
          """
          Initialize the association.
          """
          chunk = InitChunk()
          chunk.initiate_tag = self._local_verification_tag
          chunk.advertised_rwnd = self._advertised_rwnd
          chunk.outbound_streams = self._outbound_streams_count
          chunk.inbound_streams = self._inbound_streams_max
          chunk.initial_tsn = self._local_tsn
          self._set_extensions(chunk.params)
          await self._send_chunk(chunk)
  
          # start T1 timer and enter COOKIE-WAIT state
          self._t1_start(chunk)
          self._set_state(self.State.COOKIE_WAIT)