function addChangeListener(listener) {
    if (this._listeners.indexOf(listener) == -1) {
      this._log.debug("Adding change listener.");
      this._listeners.push(listener);
    }
  }
/**
   * Registers a change listener with this instance.
   *
   * Change listeners are called every time a change is recorded. The listener
   * is an object with the function "changeListener" that takes 3 arguments,
   * the Date at which the change happened, the type of change (a CHANGE_*
   * constant), and the add-on state object reflecting the current state of
   * the add-on at the time of the change.
   *
   * @param listener
   *        Object containing changeListener function.
   */
Registers a change listener with this instance.
Change listeners are called every time a change is recorded. The listener
is an object with the function "changeListener" that takes 3 arguments,
the Date at which the change happened, the type of change (a CHANGE_
constant), and the add-on state object reflecting the current state of
the add-on at the time of the change.

@param listener
Object containing changeListener function.
Registers a change listener with this instance . Change listeners are called every time a change is recorded . The listener is an object with the function " changeListener " that takes 3 arguments the Date at which the change happened the type of change ( a CHANGE_ constant ) and the add - on state object reflecting the current state of the add - on at the time of the change . @param listener Object containing changeListener function .
function addChangeListener(listener) {
    if (this._listeners.indexOf(listener) == -1) {
      this._log.debug("Adding change listener.");
      this._listeners.push(listener);
    }
  }
function addChangeListener ( listener ) { if ( this . _listeners . indexOf ( listener ) == - 1 ) { this . _log . debug ( "Adding change listener." ) ; this . _listeners . push ( listener ) ; } }
Registers a change listener with this instance.
Registers a change listener with this instance .