code: def test_number_of_neighbors(self):
      self.graph.add_edges_from([("a", "b"), ("b", "c")])
      self.assertEqual(len(list(self.graph.neighbors("b"))), 2)
  
imports: from pgmpy.base import UndirectedGraph
  from pgmpy.tests import help_functions
  import unittest
label_desc: Use image node_id 14 for calling the TestUndirectedGraphCreation obj's underlying member method code with example usage: obj.test_number_of_neighbors() without return types