code: def testSingleEdgeRetrieval(self):
      g = Graph.Famous("krackhardt_kite")
      for v1, v2 in g.get_edgelist():
          self.assertEqual(g[v1, v2], 1)
          self.assertEqual(g[v2, v1], 1)
      for v1 in range(g.vcount()):
          for v2 in set(range(g.vcount())) - set(g.neighbors(v1)):
              self.assertEqual(g[v1, v2], 0)
              self.assertEqual(g[v2, v1], 0)
  
      g.add_edge(1, 1)
      self.assertEqual(g[1, 1], 1)
  
file_path: python-igraph/tests/test_indexing.py
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 1 for calling the GraphAdjacencyMatrixLikeIndexingTests obj's underlying member method code with example usage: obj.testSingleEdgeRetrieval() without return types