docstr: Returns the zipline.utils.calendar.trading_calendar used to read
  the data.  Can be None (if the writer didn't specify it).
docstr_tok: ["Returns","the","zipline.utils.calendar.trading_calendar","used","to","read","the","data",".","Can","be","None","(","if","the","writer","did","n't","specify","it",")","."]
code: def trading_calendar(self):
      """
      Returns the zipline.utils.calendar.trading_calendar used to read
      the data.  Can be None (if the writer didn't specify it).
      """
      return self._bar_reader.trading_calendar
  
imports: import numpy
  import pandas
  from zipline.data.session_bars import SessionBarReader
label_desc: Use image node_id 4 for calling the ContinuousFutureSessionBarReader obj's underlying member method code with example usage: obj.trading_calendar() and returns: self