code: def get_index_node(self, idx):
          '''get node with iterindex `idx`'''
          idx = self.node_index.index(idx)
          return self.nodes[idxf get_index_node(self, idx):
          '''get node with iterindex `idx`'''
          idx = self.node_index.index(idx)
          return self.nodes[idx]
docs: get node with iterindex `idx`