class_docstr: Tests for query cancellation.
class_docstr_tok: ["Tests","for","query","cancellation","."]
code: def setUp(self):
      ConnectingTestCase.setUp(self)
      self.conn.set_isolation_level(ISOLATION_LEVEL_SERIALIZABLE)
  
imports: import threading
  import unittest
  from .testutils import ConnectingTestCase, skip_before_postgres, slow
  from .testutils import skip_if_crdb
  import psycopg2
  from psycopg2.extensions import ISOLATION_LEVEL_SERIALIZABLE, STATUS_BEGIN, STATUS_READY
label_desc: Use image node_id 1 for calling the QueryCancellationTests obj's underlying member method code with example usage: obj.setUp() without return types