code: def testHexagonalLattice(self):
      el = [
          (0, 1),
          (0, 6),
          (1, 2),
          (2, 3),
          (2, 8),
          (3, 4),
          (4, 10),
          (5, 6),
          (5, 11),
          (6, 7),
          (7, 8),
          (7, 13),
          (8, 9),
          (9, 10),
          (9, 15),
          (11, 12),
          (12, 13),
          (13, 14),
          (14, 15),
      ]
      g = Graph.Hexagonal_Lattice([2, 2])
      self.assertEqual(sorted(g.get_edgelist()), el)
  
      g = Graph.Hexagonal_Lattice([2, 2], directed=True, mutual=False)
      self.assertEqual(sorted(g.get_edgelist()), el)
  
      g = Graph.Hexagonal_Lattice([2, 2], directed=True, mutual=True)
      self.assertEqual(
          sorted(g.get_edgelist()), sorted(el + [(y, x) for x, y in el])
      )
  
imports: import unittest
  from igraph import Graph, InternalError
label_desc: Use image node_id 6 for calling the GeneratorTests obj's underlying member method code with example usage: obj.testHexagonalLattice() without return types