code: def add_download(self, info, future):
          
          if self.gpmon.has_plugin('Downloads'):
              obj = self.gpmon.get_plugin('Downloads')
              self.gui_do(obj.add_download, info, future)
          else:
              self.show_error("Please activate the 'Downloads' plugin to"
                              " enable download functionality")
docs: Hand off a download to the Downloads plugin, if it is present.
  
          Parameters
          ----------
          info : `~ginga.misc.Bunch.Bunch`
              A bunch of information about the URI as returned by
              `ginga.util.iohelper.get_fileinfo()`
  
          future : `~ginga.misc.Future.Future`
              A future that represents the future computation to be performed
              after downloading the file.  Resolving the future will trigger
              the computation.