Parameters:
         state_dict (dict) -- optimizer state; should be an
         object returned from a call to "state_dict()".
  Raises:
     **RuntimeError** -- if "overlap_with_ddp=True" and this
     method is     called before this "ZeroRedundancyOptimizer"
     instance     has been fully initialized, which happens once
     "DistributedDataParallel" gradient buckets have been
     rebuilt.

state_dict()
  Returns the last global optimizer state known to this rank.

  Raises:
     **RuntimeError** -- if "overlap_with_ddp=True" and this
     method is     called before this "ZeroRedundancyOptimizer"
     instance     has been fully initialized, which happens once
     "DistributedDataParallel" gradient buckets have been
     rebuilt; or if this method is called without a preceding call
     to "consolidate_state_dict()".

  Return type:
     *Dict*[str, *Any*]

step(closure=None, **kwargs)