docs: def choose(self):
          """Choose repositories
          """
          keys = """
  Choose repositories at the right side for enable or to the
  left side for disable.
  
  Keys: SPACE   select or deselect the highlighted repositories,
               move it between the left and right lists
            ^       move the focus to the left list
            $       move the focus to the right list
          TAB     move focus
        ENTER   press the focused button
  
        Disabled  <-------- REPOSITORIES ------->  Enabled"""
          self.read_enabled()
          self.read_disabled()
          text, title, backtitle, status = keys, " Repositories ", "", False
          self.selected = DialogUtil(self.disabled, text, title, backtitle,
                                     status).buildlist(self.enabled)
          if self.selected is not None:
              self.update_repos()
          else:
              self.selected = self.enabled
          self.clear_screen()
          self.reference()