code: def test_contains_order(self):
      # Sequences must test in-order.  If a rich comparison has side
      # effects, these will be visible to tests against later members.
      # In this test, the "side effect" is a short-circuiting raise.
      class DoNotTestEq(Exception):
          pass
  
      class StopCompares:
          def __eq__(self, other):
              raise DoNotTestEq
  
      checkfirst = self.type2test([1, StopCompares()])
      self.assertIn(1, checkfirst)
      checklast = self.type2test([StopCompares(), 1])
      self.assertRaises(DoNotTestEq, checklast.__contains__, 1)
  
imports: import unittest
  import sys
  import pickle
  from test import support
  from test.support import ALWAYS_EQ, NEVER_EQ
  from itertools import chain
label_desc: Use image node_id 7 for calling the CommonTest obj's underlying member method code with example usage: obj.test_contains_order() without return types