code: def test_sanity_check_session_lengths(self):
      # make sure that no session is longer than self.MAX_SESSION_HOURS hours
      for session in self.calendar.all_sessions:
          o, c = self.calendar.open_and_close_for_session(session)
          delta = c - o
          self.assertTrue(
              (delta.seconds / 3600) <= self.MAX_SESSION_HOURS
          )
  
imports: from datetime import time
  from os.path import abspath, dirname, join
  from unittest import TestCase
  import numpy
  import pandas
  from nose_parameterized import parameterized
  from pandas import read_csv
  from pandas.tslib import Timedelta
  from pandas.util.testing import assert_index_equal
  from pytz import timezone
  from toolz import concat
  from catalyst.errors import CalendarNameCollision, InvalidCalendarName
  from catalyst.testing.predicates import assert_equal
  from catalyst.utils.calendars import deregister_calendar, get_calendar, register_calendar
  from catalyst.utils.calendars.calendar_utils import _default_calendar_aliases, _default_calendar_factories, register_calendar_type
  from catalyst.utils.calendars.trading_calendar import days_at_time, TradingCalendar
label_desc: Use image node_id 3 for calling the ExchangeCalendarTestBase obj's underlying member method code with example usage: obj.test_sanity_check_session_lengths() without return types