code: def getParameterArrayCount(self, name, index):
      
      if name.startswith('_'):
        raise Exception('Parameter name must not start with an underscore')
  
      return len(self.parameters[name])
docs: Default implementation that return the length of the attribute.
  
      This default implementation goes hand in hand with
      :meth:`~nupic.bindings.regions.PyRegion.PyRegion.getParameterArray`.
      If you override one of them in your subclass, you should probably override
      both of them.
  
      The implementation prevents accessing parameters names that start with
      ``_``. It may be better to enforce this convention at the node spec level.
  
      :param name: (string) name of requested parameter
      :param index: (int) index of node inside the region (if relevant)
      :raises: Exception if parameter starts with ``_``.