code: def read_data_event(self, whence, complete=False, can_flush=False):
          
          return Transition(None, _read_data_handler(whence, self, complete, can_flush))
docs: Creates a transition to a co-routine for retrieving data as bytes.
  
          Args:
              whence (Coroutine): The co-routine to return to after the data is satisfied.
              complete (Optional[bool]): True if STREAM_END should be emitted if no bytes are read or
                  available; False if INCOMPLETE should be emitted in that case.
              can_flush (Optional[bool]): True if NEXT may be requested after INCOMPLETE is emitted as a result of this
                  data request.