code: def store_item(self, item):
          ''' use this function to store a python object in the database '''
          assert not isinstance(item, RamGraphDBNode)
          item_hash = graph_hash(item)
          if item_hash not in self.nodes:
              self.nodes[item_hash] = RamGraphDBNode(item)
          return self.nodes[item_hashf store_item(self, item):
          ''' use this function to store a python object in the database '''
          assert not isinstance(item, RamGraphDBNode)
          item_hash = graph_hash(item)
          if item_hash not in self.nodes:
              self.nodes[item_hash] = RamGraphDBNode(item)
          return self.nodes[item_hash]
docs: use this function to store a python object in the database