code: func GetDelta(base, target plumbing.EncodedObject) (plumbing.EncodedObject, error) {
  	return getDelta(new(deltaIndex), base, target)
  }
docs: // GetDelta returns an EncodedObject of type OFSDeltaObject. Base and Target object,
  // will be loaded into memory to be able to create the delta object.
  // To generate target again, you will need the obtained object and "base" one.
  // Error will be returned if base or target object cannot be read.