nl_tokens: check whether mixin is in inherited chain of child class
pl_tokens: function subOf ( child , mixin ) { if ( child === mixin ) return true ; if ( child && child . constructors ) { for ( var i in child . constructors ) { var parent = child . constructors [ i ] ; // avoid dead loop if ( parent === child ) continue ; if ( parent === mixin ) return true ; if ( subOf ( parent , mixin ) ) return true ; } } return <mask> ; }