code: def _decayPoolingActivation(self):
      
      if self._decayFunctionType == 'NoDecay':
        self._poolingActivation = self._decayFunction.decay(self._poolingActivation)
      elif self._decayFunctionType == 'Exponential':
        self._poolingActivation = self._decayFunction.decay(\
                                  self._poolingActivationInitLevel, self._poolingTimer)
  
      return self._poolingActivation
docs: Decrements pooling activation of all cells