code: function(adjustment, precision, captions, callback) {
          //precision should be one of: seconds, milliseconds, microseconds
          var precisionMultipliers = {
                  "seconds": 1000000, //seconds to microseconds
                  "milliseconds": 1000, //milliseconds to microseconds
                  "microseconds": 1 //microseconds to microseconds
              },
              newStartTime,
              newEndTime,
              adjuster = adjustment * precisionMultipliers[precision];
          if (precisionMultipliers[precision] && captions[0].startTimeMicro !== undefined) {
              //quick check to see if it will zero out the 2nd or 3rd caption
              // there are cases where the first caption can be 00:00:00:000 and have no text.
              if ((captions[1].startTimeMicro + adjuster) <= 0 || (captions[2].startTimeMicro + adjuster) <= 0) {
                  return callback("ERROR_ADJUSTMENT_ZEROS_CAPTIONS");
              }
              captions.forEach(function(caption) {
                  //calculate new start times...
                  newStartTime = caption.startTimeMicro + adjuster;
                  newEndTime = caption.endTimeMicro + adjuster;
                  if (adjuster > 0) {
                      caption.startTimeMicro = newStartTime;
                      caption.endTimeMicro = newEndTime;
                  } else if (newStartTime >= 0 && newEndTime >= 0) {
                      caption.startTimeMicro = newStartTime;
                      caption.endTimeMicro = newEndTime;
                  }
              });
              callback(undefined, captions);
          } else {
              callback('NO_CAPTIONS_OR_PRECISION_PASSED_TO_FUNCTION');
          }
      }
docs: adjust timestamp by X, precision
  @function
  @param {integer} adjustment - negative or positive integer amount to adjust the captions by
  @param {string} precision - precision to adjust captions by
  @param {array} captions - json array of captions to perform adjustment on created by toJSON
  @public