def get_summary(self, timezone_offset, first_date, start=0.0, end=0.0):

        ''' a method to retrieve summary details for a period of time

        NOTE: start and end must be no more than 30 days, 1 second apart

        :param timezone_offset: integer with timezone offset from user profile details
        :param first_date: string with ISO date from user profile details firstDate
        :param start: [optional] float with starting datetime for daily summaries
        :param end: [optional] float with ending datetime for daily summaries
        :return: dictionary of response details with summary list inside json key

         {
            'headers': { ... },
            'code': 200,
            'error': '',
            'url': 'https://api.moves-app.com/api/1.1/user/summary/daily'
            'json': [ SEE RESPONSE in https://dev.moves-app.com/docs/api_summaries ]
        }
        '''

        title = '%s.get_summary' % self.__class__.__name__

    # validate scope
        if 'activity' not in self.service_scope:
            raise ValueError('%s requires service scope to contain "activity".' % title)

    # construct request fields
        url_string = '%s/user/summary/daily' % self.endpoint
        parameters = self._process_dates(timezone_offset, first_date, start, end, title)

    # send request
        response_details = self._get_request(url_string, params=parameters)

        return response_details