code: def get_parent_objective_bank_nodes(self):
          
          parent_objective_bank_nodes = []
          for node in self._my_map['parentNodes']:
              parent_objective_bank_nodes.append(ObjectiveBankNode(
                  node._my_map,
                  runtime=self._runtime,
                  proxy=self._proxy,
                  lookup_session=self._lookup_session))
          return ObjectiveBankNodeList(parent_objective_bank_nodes)
docs: Gets the parents of this objective bank.
  
          return: (osid.learning.ObjectiveBankNodeList) - the parents of
                  the ``id``
          *compliance: mandatory -- This method must be implemented.*