nl_tokens: Create model class with a subscribable interface .
pl_tokens: function ( parentClass , constructor ) { // inherits methods from parent class constructor . prototype = Object . create ( parentClass . prototype ) ; // inherits methods from Subscribable class  for ( var key in Subscribable . prototype ) { constructor . prototype [ <mask> ] = Subscribable . prototype [ key ] ; } constructor . prototype . constructor = constructor ; constructor . prototype . _keepHot = true ; return constructor ; }