code: def testAddition(self):
      g0 = Graph.Full(3)
  
      # Adding vertices
      g = g0 + 2
      self.assertTrue(
          g.vcount() == 5
          and g.ecount() == 3
          and g.connected_components().membership == [0, 0, 0, 1, 2]
      )
      g0 = g
  
      # Adding vertices by name
      g = g0 + "spam"
      self.assertTrue(
          g.vcount() == 6
          and g.ecount() == 3
          and g.connected_components().membership == [0, 0, 0, 1, 2, 3]
      )
      g0 = g
  
      # Adding a single edge
      g = g0 + (2, 3)
      self.assertTrue(
          g.vcount() == 6
          and g.ecount() == 4
          and g.connected_components().membership == [0, 0, 0, 0, 1, 2]
      )
      g0 = g
  
      # Adding two edges
      g = g0 + [(3, 4), (2, 4), (4, 5)]
      self.assertTrue(
          g.vcount() == 6
          and g.ecount() == 7
          and g.connected_components().membership == [0] * 6
      )
      g0 = g
  
      # Adding another graph
      g = g0 + Graph.Full(3)
      self.assertTrue(
          g.vcount() == 9
          and g.ecount() == 10
          and g.connected_components().membership
          == [0, 0, 0, 0, 0, 0, 1, 1, 1]
      )
  
imports: import unittest
  from igraph import Graph, disjoint_union, intersection, union
label_desc: Use image node_id 24 for calling the OperatorTests obj's underlying member method code with example usage: obj.testAddition() without return types