b.lastRuneSize = size
	return r, size, nil
}

// UnreadRune unreads the last rune. If the most recent method called on
// the [Reader] was not a [Reader.ReadRune], [Reader.UnreadRune] returns an error. (In this
// regard it is stricter than [Reader.UnreadByte], which will unread the last byte
// from any read operation.)
func (b *Reader) UnreadRune() error {
	if b.lastRuneSize < 0 || b.r < b.lastRuneSize {
		return ErrInvalidUnreadRune

}

// UnreadRune unreads the last rune returned by [Buffer.ReadRune].
// If the most recent read or write operation on the buffer was
// not a successful [Buffer.ReadRune], UnreadRune returns an error.  (In this regard
// it is stricter than [Buffer.UnreadByte], which will unread the last byte
// from any read operation.)
func (b *Buffer) UnreadRune() error {
	if b.lastRead <= opInvalid {

    author_link: https://testdriven.io/authors/herman
    link: https://testdriven.io/blog/fastapi-crud/
    title: 'TestDriven.io: Developing and Testing an Asynchronous API with FastAPI and Pytest'
  - author: Bernard Brenyah
    author_link: https://medium.com/@bbrenyah
    link: https://medium.com/python-data/how-to-deploy-tensorflow-2-0-models-as-an-api-service-with-fastapi-docker-128b177e81f3

   *     lower-case characters
   */
  public abstract BaseEncoding lowerCase();

  /**
   * Returns an encoding that behaves equivalently to this encoding, but decodes letters without
   * regard to case.
   *
   * @throws IllegalStateException if the alphabet used by this encoding contains mixed upper- and
   *     lower-case characters
   * @since 32.0.0
   */
  public abstract BaseEncoding ignoreCase();