docs: def on_install(self, editor):
          """
          Add the folding menu to the editor, on install.
  
          :param editor: editor instance on which the mode has been installed to.
          """
          super(FoldingPanel, self).on_install(editor)
          self.context_menu = QtWidgets.QMenu(_('Folding'), self.editor)
          action = self.action_collapse = QtWidgets.QAction(
              _('Collapse'), self.context_menu)
          action.setShortcut('Shift+-')
          action.triggered.connect(self._on_action_toggle)
          self.context_menu.addAction(action)
          action = self.action_expand = QtWidgets.QAction(_('Expand'),
                                                          self.context_menu)
          action.setShortcut('Shift++')
          action.triggered.connect(self._on_action_toggle)
          self.context_menu.addAction(action)
          self.context_menu.addSeparator()
          action = self.action_collapse_all = QtWidgets.QAction(
              _('Collapse all'), self.context_menu)
          action.setShortcut('Ctrl+Shift+-')
          action.triggered.connect(self._on_action_collapse_all_triggered)
          self.context_menu.addAction(action)
          action = self.action_expand_all = QtWidgets.QAction(
              _('Expand all'), self.context_menu)
          action.setShortcut('Ctrl+Shift++')
          action.triggered.connect(self._on_action_expand_all_triggered)
          self.context_menu.addAction(action)
          self.editor.add_menu(self.context_menu)