docs: function(str, formats) {
      // first, replace any ORDERED replacements.
      var idx  = 0; // the current index for non-numerical replacements
      return str.replace(/%@([0-9]+)?/g, function(s, argIndex) {
        argIndex = (argIndex) ? parseInt(argIndex,0) - 1 : idx++ ;
        s = formats[argIndex];
        return ((s === null) ? '(null)' : (s === undefined) ? '' : s).toString();
      }) ;
    }