code: func ParseAnyReference(ref string) (Reference, error) {
  	if ok := anchoredIdentifierRegexp.MatchString(ref); ok {
  		return digestReference("sha256:" + ref), nil
  	}
  	if dgst, err := digest.Parse(ref); err == nil {
  		return digestReference(dgst), nil
  	}
  
  	return ParseNormalizedNamed(ref)
  }
docs: // ParseAnyReference parses a reference string as a possible identifier,
  // full digest, or familiar name.