nl_tokens: Returns a function observing changes on an end of the link . If a change happens and new end is a new model it stops listening on the previous one and starts listening to the new one .
pl_tokens: function ( endType ) { function watchEnd ( link , <mask> ) { end = end || { } ; var previousEnd = link . previous ( endType ) || { } ; // Pick updateMethod this._sourceBboxUpdate or this._targetBboxUpdate. var updateEndFunction = this [ '_' + endType + 'BBoxUpdate' ] ; if ( this . _isModel ( previousEnd ) ) { this . stopListening ( this . paper . getModelById ( previousEnd . id ) , 'change' , updateEndFunction ) ; } if ( this . _isModel ( end ) ) { // If the observed model changes, it caches a new bbox and do the link update. this . listenTo ( this . paper . getModelById ( end . id ) , 'change' , updateEndFunction ) ; } _ . bind ( updateEndFunction , this ) ( { cacheOnly : true } ) ; return this ; } return watchEnd ; }