code: def set_backward_passes_per_step(self, passes):
      self.backward_passes_per_step = passes
      for p in self._push_pull_delay:
          self._push_pull_delay[p] = self.backward_passes_per_step
  
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 3 for calling the _HalfPrecisionDistributedOptimizer obj's underlying member method code with example usage: obj.set_backward_passes_per_step(passes) without return types