code: function msg(str) {
  	if (str == null) {
  		return null;
  	}
  
  	for (var i = 1, len = arguments.length; i < len; ++i) {
  		str = str.replace('{' + (i - 1) + '}', String(arguments[i]));
  	}
  
  	return str;
  }
docs: Interpolates a string with the arguments, used for error messages.
  @private