code: func (iter *MultiReferenceIter) ForEach(cb func(*plumbing.Reference) error) error {
  	return forEachReferenceIter(iter, cb)
  }
docs: // ForEach call the cb function for each reference contained on this iter until
  // an error happens or the end of the iter is reached. If ErrStop is sent
  // the iteration is stop but no error is returned. The iterator is closed.