code: def update(self, grads):
      for key, grad in iteritems(grads):
          param = self.params[key]
          self._update_impl(key, param, grad)
      self.weight_decay_rate = self.default_weight_decay_rate.copy()
  
imports: from six import iteritems
  import nnabla
  import nnabla.solvers
  from nnabla.testing import assert_allclose
  import numpy
  from collections import OrderedDict
  import os
label_desc: Use image node_id 5 for calling the RefSolver obj's underlying member method code with example usage: obj.update(grads) without return types