code: function(captions) {
          var VTT_BODY = ['WEBVTT\n']; //header
          captions.forEach(function(caption) {
              if (caption.text.length > 0 && validateText(caption.text)) {
                  VTT_BODY.push(module.exports.formatTime(caption.startTimeMicro) + ' --> ' + module.exports.formatTime(caption.endTimeMicro));
                  VTT_BODY.push(module.exports.renderMacros(caption.text) + '\n');
              }
          });
          return VTT_BODY.join('\n');
      }
docs: Generates VTT from JSON
  @function
  @param {array} captions - array of json captions
  @public