code: def wd(self, val:float)->None:
          "Set weight decay."
          if not self.true_wd: self.set_val('weight_decay', listify(val, self._wd), bn_groups=self.bn_wd)
          self._wd = listify(val, self._wdf wd(self, val:float)->None:
          "Set weight decay."
          if not self.true_wd: self.set_val('weight_decay', listify(val, self._wd), bn_groups=self.bn_wd)
          self._wd = listify(val, self._wd)
docs: Set weight decay.