code: def trading_calendar(self):
      return self._trading_calendar
  
imports: import logbook
  import pandas
  from zipline.utils.memoize import remember_last
  from zipline.utils.pandas_utils import normalize_date
label_desc: Use image node_id 12 for calling the SimulationParameters obj's underlying member method code with example usage: obj.trading_calendar() and returns: self