code: def test_async_cursor_gone(self):
      cur = self.conn.cursor()
      cur.execute("select 42;")
      del cur
      gc.collect()
      self.assertRaises(psycopg2.InterfaceError, self.wait, self.conn)
  
      # The connection is still usable
      cur = self.conn.cursor()
      cur.execute("select 42;")
      self.wait(self.conn)
      self.assertEqual(cur.fetchone(), (42,))
  
imports: import gc
  import time
  import unittest
  import warnings
  import psycopg2
  import psycopg2.errors
  from psycopg2 import extensions
  from .testutils import ConnectingTestCase, StringIO, skip_before_postgres, skip_if_crdb, crdb_version, slow
label_desc: Use image node_id 28 for calling the AsyncTests obj's underlying member method code with example usage: obj.test_async_cursor_gone() without return types