code: def setUpClass(cls):
      cls.nyse_calendar = get_calendar("NYSE")
  
      # july 15 is friday, so there are 3 sessions in this range (15, 18, 19)
      cls.sessions = cls.nyse_calendar.sessions_in_range(
          pd.Timestamp("2016-07-15"), pd.Timestamp("2016-07-19")
      )
  
      trading_o_and_c = cls.nyse_calendar.schedule.ix[cls.sessions]
      cls.opens = trading_o_and_c["market_open"]
      cls.closes = trading_o_and_c["market_close"]
  
file_path: zipline/tests/test_clock.py
imports: from datetime import time
  from unittest import TestCase
  import pandas
  from trading_calendars import get_calendar
  from trading_calendars.utils.pandas_utils import days_at_time
  from zipline.gens.sim_engine import MinuteSimulationClock, SESSION_START, BEFORE_TRADING_START_BAR, BAR, SESSION_END
label_desc: Use image node_id 1 for calling the TestClock obj's underlying member method code with example usage: obj.setUpClass(cls) without return types