code: func (iter *referenceFilteredIter) Next() (*plumbing.Reference, error) {
  	for {
  		r, err := iter.iter.Next()
  		if err != nil {
  			return nil, err
  		}
  
  		if iter.ff(r) {
  			return r, nil
  		}
  
  		continue
  	}
  }
docs: // Next returns the next reference from the iterator. If the iterator has reached
  // the end it will return io.EOF as an error.