code: public static Track getTrackingInfo(String carrier, String trackingNumber, String apiKey)
  			throws AuthenticationException, InvalidRequestException, APIConnectionException, APIException {
  		return request(RequestMethod.GET, trackingNumberURL(carrier, trackingNumber), null, Track.class, apiKey);
  	}
docs: Get tracking information of any package from given carrier. This
  corresponds to https://api.goshippo.com/tracks/<i>carrier</i>/<i>tracking_number</i>
  API defined in https://goshippo.com/docs/reference#tracks-retrieve
  
  @param carrier
  Name of the carrier (like "usps") tracking the package
  @param trackingNumber
  Tracking number provided by the carrier for a package
  @return Track object containing tracking info