code: def testCohesiveBlockingErrors(self):
      g = Graph.GRG(100, 0.2)
      g.to_directed()
      self.assertRaises(InternalError, g.cohesive_blocks)
  
imports: import math
  import random
  import unittest
  from igraph import Clustering, CohesiveBlocks, Cover, Graph, Histogram, InternalError, UniqueIdGenerator, VertexClustering, compare_communities, split_join_distance, set_random_number_generator
label_desc: Use image node_id 4 for calling the CohesiveBlocksTests obj's underlying member method code with example usage: obj.testCohesiveBlockingErrors() without return types