code: def getDatastreamHistory(self, pid, dsid, format=None):
          '''Get history information for a datastream.
  
          :param pid: object pid
          :param dsid: datastream id
          :param format: format
          :rtype: :class:`requests.models.Response`
          '''
          http_args = {}
          if format is not None:
              http_args['format'] = format
          # Fedora docs say the url should be:
          #   /objects/{pid}/datastreams/{dsid}/versions
          # In Fedora 3.4.3, that 404s but /history does not
          uri = 'objects/%(pid)s/datastreams/%(dsid)s/history' % \
              {'pid': pid, 'dsid': dsid}
          return self.get(uri, params=http_argsf getDatastreamHistory(self, pid, dsid, format=None):
          '''Get history information for a datastream.
  
          :param pid: object pid
          :param dsid: datastream id
          :param format: format
          :rtype: :class:`requests.models.Response`
          '''
          http_args = {}
          if format is not None:
              http_args['format'] = format
          # Fedora docs say the url should be:
          #   /objects/{pid}/datastreams/{dsid}/versions
          # In Fedora 3.4.3, that 404s but /history does not
          uri = 'objects/%(pid)s/datastreams/%(dsid)s/history' % \
              {'pid': pid, 'dsid': dsid}
          return self.get(uri, params=http_args)
docs: Get history information for a datastream.
  
          :param pid: object pid
          :param dsid: datastream id
          :param format: format
          :rtype: :class:`requests.models.Response`