code: def add_catalog_from_URL(self, votable_URL, votable_options={}):
          
          self.votable_URL= votable_URL
          self.votable_options= votable_options
          self.votable_from_URL_flag= not self.votable_from_URL_flag
docs: load a VOTable table from an url and load its data into the widget 
              Args:
                  votable_URL: string url
                  votable_options: dictionary object