docstr: Clears the gradients of all optimized parameters.
docstr_tok: ["Clears","the","gradients","of","all","optimized","parameters","."]
code: def zero_grad(self):
      """Clears the gradients of all optimized parameters."""
      for p in self.params:
          p.grad = None
      self.optimizer.zero_grad()
  
imports: import torch
  from fairseq import utils
  from fairseq.dataclass.utils import gen_parser_from_dataclass
  from collections import defaultdict
label_desc: Use image node_id 18 for calling the FairseqOptimizer obj's underlying member method code with example usage: obj.zero_grad() without return types