docs: def group_write(self, addr, data, dptsize=0):
          """Send a group write to the given address.
  
          The method does not check if the address exists and the write request
          is valid.
          """
          cemi = CEMIMessage()
          cemi.init_group_write(addr, data, dptsize)
  
          with self._lock:
              self.send_tunnelling_request(cemi)
              # Workaround for lost KNX packets
              if self._write_delay: 
                  time.sleep(self._write_delay)