code: def test_append() -> None:
      dim = 4
      multilist = VectorLinkedList(dimension=dim)
  
      new_node = VectorNode(dim)
      multilist.append(new_node, 0)
  
      for i in range(1, dim):
          assert new_node.next[i] is new_node
          assert new_node.prev[i] is new_node
          assert multilist.sentinel.next[i] is multilist.sentinel
          assert multilist.sentinel.prev[i] is multilist.sentinel
  
      assert new_node.next[0] is multilist.sentinel
      assert new_node.prev[0] is multilist.sentinel
      assert multilist.sentinel.next[0] is new_node
      assert multilist.sentinel.prev[0] is new_node
  
      another_node = VectorNode(dim)
      multilist.append(another_node, 0)
      for i in range(1, dim):
          assert new_node.next[i] is new_node
          assert new_node.prev[i] is new_node
          assert multilist.sentinel.next[i] is multilist.sentinel
          assert multilist.sentinel.prev[i] is multilist.sentinel
  
      assert new_node.next[0] is another_node
      assert new_node.prev[0] is multilist.sentinel
      assert multilist.sentinel.next[0] is new_node
      assert multilist.sentinel.prev[0] is another_node
  
file_path: nevergrad/nevergrad/optimization/multiobjective/test_hypervolume.py
imports: import numpy
  from .hypervolume import VectorNode, VectorLinkedList, HypervolumeIndicator
label_desc: Use image node_id 4 for calling a global function with example usage: test_append() without return types