code: def _handle(self, req, client_address):
      if isinstance(req, RegisterTaskRequest):
          self._wait_cond.acquire()
          try:
              assert 0 <= req.index < self._num_proc
              self._all_task_addresses[req.index] = req.task_addresses
              # Just use source address for service for fast probing.
              self._task_addresses_for_driver[
                  req.index
              ] = self._filter_by_ip(
                  req.task_addresses, client_address[0]
              )
              if not self._task_addresses_for_driver[req.index]:
                  # No match is possible if one of the servers is behind NAT.
                  # We don't throw exception here, but will allow the following
                  # code fail with NoValidAddressesFound.
                  print(
                      "ERROR: Task {index} declared addresses {task_addresses}, "
                      "but has connected from a different address {source}. "
                      "This is not supported. Is the server behind NAT?"
                      "".format(
                          index=req.index,
                          task_addresses=req.task_addresses,
                          source=client_address[0],
                      )
                  )
  
              # Remove host hash earlier registered under this index.
              if req.index in self._task_index_host_hash:
                  earlier_host_hash = self._task_index_host_hash[
                      req.index
                  ]
                  if earlier_host_hash != req.host_hash:
                      self._task_host_hash_indices[
                          earlier_host_hash
                      ].remove(req.index)
  
              # Make index -> host hash map.
              self._task_index_host_hash[req.index] = req.host_hash
  
              # Make host hash -> indices map.
              if req.host_hash not in self._task_host_hash_indices:
                  self._task_host_hash_indices[req.host_hash] = []
              self._task_host_hash_indices[req.host_hash].append(
                  req.index
              )
              # TODO: this sorting is a problem in elastic horovod
              self._task_host_hash_indices[req.host_hash].sort()
          finally:
              self._wait_cond.notify_all()
              self._wait_cond.release()
          return network.AckResponse()
  
      if isinstance(req, RegisterTaskToTaskAddressesRequest):
          self.register_task_to_task_addresses(
              req.index, req.task_addresses
          )
          return network.AckResponse()
  
      if isinstance(req, AllTaskAddressesRequest):
          return AllTaskAddressesResponse(
              self._all_task_addresses[req.index]
          )
  
      return super(BasicDriverService, self)._handle(
          req, client_address
      )
  
imports: import threading
  from horovod.runner.common.util import network
label_desc: Use image node_id 2 for calling the BasicDriverService obj's underlying member method code with example usage: obj._handle(req, client_address) and returns: super, network, network, AllTaskAddressesResponse