code: func (iter *EncodedObjectSliceIter) Next() (plumbing.EncodedObject, error) {
  	if len(iter.series) == 0 {
  		return nil, io.EOF
  	}
  
  	obj := iter.series[0]
  	iter.series = iter.series[1:]
  
  	return obj, nil
  }
docs: // Next returns the next object from the iterator. If the iterator has reached
  // the end it will return io.EOF as an error. If the object is retreieved
  // successfully error will be nil.