code: def testCoverLength(self):
      self.assertTrue(len(self.cl) == 4)
  
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 3 for calling the CoverTests obj's underlying member method code with example usage: obj.testCoverLength() without return types