code: def copy(self):
          
          from .lists_and_dicts import ObserverList
          memo = {}
          memo[id(self)] = self
          memo[id(self.observers)] = ObserverList()
          return self.__deepcopy__(memo)
docs: Make a copy. This means, we delete all observers and return a copy of this
          array. It will still be an ObsAr!