code: function(code)
    {
      var lineNumbers = [],
          lines = this.lines,
          firstLine = parseInt(this.opts.firstLine || 1),
          i,
          l
          ;
  
      for (i = 0, l = lines.length; i < l; i++)
        lineNumbers.push(i + firstLine);
  
      return lineNumbers;
    }
docs: Creates an array containing integer line numbers starting from the 'first-line' param.
  @return {Array} Returns array of integers.