[hash.Cloner] if the underlying hash does. // Otherwise, it returns an error wrapping [errors.ErrUnsupported]. func (h *HMAC) Clone() (hash.Cloner, error) { r := *h ic, ok := h.inner.(hash.Cloner) if !ok { return nil, errCloneUnsupported{} } oc, ok := h.outer.(hash.Cloner) if !ok { return nil, errCloneUnsupported{} } var err error r.inner, err = ic.Clone() if err != nil { return nil, errCloneUnsupported{} } r.outer, err = oc.Clone() if err != nil { return nil, errCloneUnsupported{} } return &r, nil } //...