code: def attach(self, filt, view=None):
          
          if view is None:
              self._vshare.filters.append(filt)
              for view in self._vshare.views.keys():
                  filt._attach(view)
          else:
              view._filters.append(filt)
              filt._attach(view)
docs: Attach a Filter to this visual
  
          Each filter modifies the appearance or behavior of the visual.
  
          Parameters
          ----------
          filt : object
              The filter to attach.
          view : instance of VisualView | None
              The view to use.