code: def _wait_for_all(self):
      while len(self._handles.keys()) > 0:
          params = list(self._handles.keys())
          for p in params:
              self._try_to_synchronize(p)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from byteps.torch import _DistributedOptimizer
  from byteps.torch.compression import Compression
  from byteps.torch.ops import push_pull_async_inplace
  from byteps.torch.ops import push_pull
  from byteps.torch.ops import poll, synchronize, declare
  from byteps.torch.ops import init, shutdown
  from byteps.torch.ops import size, local_size, rank, local_rank
  import time
  import threading
  import torch
  import collections
label_desc: Use image node_id 12 for calling the _HalfPrecisionDistributedOptimizer obj's underlying member method code with example usage: obj._wait_for_all() without return types