docstr: Performs a single optimization step.
docstr_tok: ["Performs","a","single","optimization","step","."]
code: def step(self, closure=None):
      """Performs a single optimization step."""
      self._unscale_grads()
      self.wrapped_optimizer.step(closure)
  
imports: from itertools import chain
  import torch
  from fairseq import utils
  from fairseq.optim.fp16_optimizer import DynamicLossScaler
label_desc: Use image node_id 8 for calling the Fairseq_MemoryEfficientFP16OptimizerMixin obj's underlying member method code with example usage: obj.step(closure) without return types