code: def setParameter(self, parameterName, index, parameterValue):
      
      if parameterName == 'topDownMode':
        self.topDownMode = parameterValue
      elif parameterName == 'predictedField':
        self.predictedField = parameterValue
      else:
        raise Exception('Unknown parameter: ' + parameterName)
docs: Set the value of a Spec parameter. Most parameters are handled
        automatically by PyRegion's parameter set mechanism. The ones that need
        special treatment are explicitly handled here.