code: function(lineIndex, lineNumber, lineHtml)
    {
      var classes = [
        'line',
        'number' + lineNumber,
        'index' + lineIndex,
        'alt' + (lineNumber % 2 == 0 ? 1 : 2).toString()
      ];
  
      if (this.linesToHighlight[lineNumber])
        classes.push('highlighted');
  
      if (lineNumber == 0)
        classes.push('break');
  
      return '<div class="' + classes.join(' ') + '">' + lineHtml + '</div>';
    }
docs: Generates HTML markup for a single line of code while determining alternating line style.
  @param {Integer} lineNumber  Line number.
  @param {String} code Line  HTML markup.
  @return {String}       Returns HTML markup.