code: def computeEnvelope(self, placeCode):
      
      places = np.abs(placeCode - 0.5)
      envelope = [1 if p < 1 - self.envelopeWidth else
                        np.exp(-1.*self.envelopeFactor *
                        ((p - 1 + self.envelopeWidth)/self.envelopeWidth)**2)
                        for p in places]
  
      return np.asarray(envelope)
docs: Compute an envelope for use in suppressing border cells.
      :param placeCode: The place code representing the population the envelope
              will be used for.
      :return: A numpy array that can be elementwise-multiplied with activations
               for the given cell population to apply the envelope.