code: function rethrow(err, fp, str, re) {
    var lines = str.split('\n');
    var len = lines.length, i = 0;
    var res = '';
  
    while (len--) {
      var line = lines[i++];
      if (re.test(line)) {
        error(err, fp, i, str);
        break;
      }
    }
  }
docs: Re-throw an error to get the line number and
  postion to help with debuging.
  
  @param  {Error} `err` Pass an `Error` object
  @param  {Object} `fp` Pass `file.path`
  @param  {Object} `str` The content string
  @param  {Object} `re` RegExp to use for matching the template delimiters
  @return {Object}