code: def _call(self, f, out):
          
          for vfi, oi, ran_wi, dom_wi in zip(self.vecfield, out,
                                             self.__ran_weights, self.weights):
              vfi.multiply(f, out=oi)
              if not np.isclose(ran_wi, dom_wi):
                  oi *= dom_wi / ran_wi
docs: Implement ``self(vf, out)``.