code: function(str){
      if(_.isUndefined(str))
          str = '00';
      
      return String(str).length % 2 ? '0' + String(str) : String(str);
  }
docs: Pad the given string with a prefix zero, if length is uneven.
  
  @method (formatHex)
  @param {String} str    The string to pad for use as hex
  @return {String} The padded or formatted string for use as a hex string