code: def test_backref_pop_m2m(self):
      Keyword, Item = self.classes.Keyword, self.classes.Item
  
      k1 = Keyword()
      k2 = Keyword()
      i1 = Item()
      k1.items.append(i1)
      k2.items.append(i1)
      k2.items.append(i1)
      i1.keywords = []
      k2.items.remove(i1)
      assert len(k2.items) == 0
  
imports: from sqlalchemy import testing
  from sqlalchemy import text
  from sqlalchemy.orm import attributes
  from sqlalchemy.orm import backref
  from sqlalchemy.orm import relationship
  from sqlalchemy.orm import Session
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing import is_
  from sqlalchemy.testing.fixtures import fixture_session
  from test.orm import _fixtures
label_desc: Use image node_id 2 for calling the M2MStaleBackrefTest obj's underlying member method code with example usage: obj.test_backref_pop_m2m() without return types