docstr: Multiplies grads by a constant *c*.
docstr_tok: ["Multiplies","grads","by","a","constant","*","c","*","."]
code: def multiply_grads(self, c):
      """Multiplies grads by a constant *c*."""
      if self._grads_are_scaled:
          self._unscale_grads(c)
      else:
          self.wrapped_optimizer.multiply_grads(c)
  
imports: from itertools import chain
  import torch
  from fairseq import utils
  from fairseq.optim.fp16_optimizer import DynamicLossScaler
label_desc: Use image node_id 6 for calling the Fairseq_MemoryEfficientFP16OptimizerMixin obj's underlying member method code with example usage: obj.multiply_grads(c) without return types