code: def test_add_edges_from_nonstring(self):
      self.graph.add_edges_from([(1, 2), (2, 3)])
  
imports: from pgmpy.base import UndirectedGraph
  from pgmpy.tests import help_functions
  import unittest
label_desc: Use image node_id 13 for calling the TestUndirectedGraphCreation obj's underlying member method code with example usage: obj.test_add_edges_from_nonstring() without return types