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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def export_survey_participant_list(self, instrument, event=None, format='json'):
 """ Export the Survey Participant List Notes ----- The passed instrument must be set up as a survey instrument. Parameters instrument: str Name of instrument as seen in second column of Data Dictionary. event: str Unique event name, only used in longitudinal projects format: (json, xml, csv), json by default Format of returned data """

        pl = self.__basepl(content='participantList', format=format)
        pl['instrument'] = instrument
        if event:
            pl['event'] = event
        return self._call_api(pl, 'exp_survey_participant_list')