code: def test_async_select(self):
      cur = self.conn.cursor()
      self.assertFalse(self.conn.isexecuting())
      cur.execute("select 'a'")
      self.assertTrue(self.conn.isexecuting())
  
      self.wait(cur)
  
      self.assertFalse(self.conn.isexecuting())
      self.assertEquals(cur.fetchone()[0], "a")
  
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 4 for calling the AsyncTests obj's underlying member method code with example usage: obj.test_async_select() without return types