code: def _is_all_zero(self, param_groups):
      for p in self._generate_params(param_groups):
          for u in p.grad.data:
              for v in u:
                  self.assertEqual(v.float(), 0.0)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import copy
  import unittest
  import torch
  from pytext.optimizer import fp16_optimizer
  from torch.autograd import Variable
label_desc: Use image node_id 21 for calling the TestFp16Optimizer obj's underlying member method code with example usage: obj._is_all_zero(param_groups) without return types