add: this.ds.Unassert (n1, a, n2)  
context: function rdf_duassert (n1, a, n2){    var oldN2 = this.ds.GetTarget (n1, a, true);    if (!oldN2)    {        dd ("** Unable to change " + n1.Value + " -[" + a.Value + "]->, " +            "because old value was not found.");        return null;    }        return this.ds.Change (n1, a, oldN2, n2);    }
meta: 1622	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/1622/7989b1857bd846d061fcfb0a35c564855021bf24/rdf.js/buggy/xul/content/rdf.js