nl_tokens: Observer is a subscribable which watches a function and each time some variable in it changes it is called again and its return value is passed to subscribers .
pl_tokens: function Observer ( fn , observerInfo ) { // call Subscribable constructor Subscribable . call ( this ) ; this . fn = fn ; this . dependency = [ ] ; this . currentValue = null ; this . observerInfo = observerInfo ; // hard binded callbacks this . _dependencyGetter = this . dependencyGetter . bind ( this ) ; this . <mask> ( ) ; }