return this.lineMap[lineNo]; 
return this.lineMap ? this.lineMap[lineNo] : false; 
    isInExecutableTable: function(lineNo)    {        return this.lineMap[lineNo];    }
2454	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/2454/657c1059e813834f821277cbe0ed6b432bead8b9/lib.js/buggy/extension/content/firebug/lib.js