code: def requested_extent(self, extent):
          
          if isinstance(extent, QgsRectangle):
              self._requested_extent = extent
              self._is_ready = False
          else:
              raise InvalidExtentError('%s is not a valid extent.' % extent)
docs: Setter for extent property.
  
          :param extent: Analysis boundaries expressed as a QgsRectangle.
              The extent CRS should match the crs property of this IF
              instance.
          :type extent: QgsRectangle