code: function _startNewSession(editor) {
          if (isOpen()) {
              return;
          }
  
          if (!editor) {
              editor = EditorManager.getFocusedEditor();
          }
          if (editor) {
              lastChar = null;
              if (_inSession(editor)) {
                  _endSession();
              }
  
              // Begin a new explicit session
              _beginSession(editor);
          }
      }
docs: Explicitly start a new session. If we have an existing session,
  then close the current one and restart a new one.
  @param {Editor} editor