code: function format(f) {
      "use strict";
      var i = 1;
      var args = arguments;
      var len = args.length;
      var str = String(f).replace(/%[sdj%]/g, function _replace(x) {
          if (i >= len) return x;
          switch (x) {
          case '%s':
              return String(args[i++]);
          case '%d':
              return Number(args[i++]);
          case '%j':
              return JSON.stringify(args[i++]);
          case '%%':
              return '%';
          default:
              return x;
          }
      });
      for (var x = args[i]; i < len; x = args[++i]) {
          if (x === null || typeof x !== 'object') {
              str += ' ' + x;
          } else {
              str += '[obj]';
          }
      }
      return str;
  }
docs: Formats a string with passed parameters. Ported from nodejs `util.format()`.
  
  @return String