code: def test_sync_poll(self):
      cur = self.sync_conn.cursor()
      cur.execute("select 1")
      # polling with a sync query works
      cur.connection.poll()
      self.assertEquals(cur.fetchone()[0], 1)
  
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 21 for calling the AsyncTests obj's underlying member method code with example usage: obj.test_sync_poll() without return types