docs: def usage(self, period=None, start=None, end=None):
          """ Get account usage information
  
              :param period: Period is one of either hourly, daily or monthly
              :type period: str
              :param start: Determines time period of the usage
              :type start: int
              :param end: Determines time period of the usage
              :type end: int
              :return: dict of REST API output with headers attached
              :rtype: :class:`~datasift.request.DictResponse`
              :raises: :class:`~datasift.exceptions.DataSiftApiException`,
                  :class:`requests.exceptions.HTTPError`
          """
  
          params = {}
  
          if period:
              params['period'] = period
          if start:
              params['start'] = start
          if end:
              params['end'] = end
  
          return self.request.get('usage', params)