input: from typing import Callable
  
  def create_celery_task(app: Celery, mail: Callable) -> Callable:
      """Create a Celery task to send an email.
      >>> create_celery_task(app, mail)
      <function send_email at 0x...>
      >>> send_email('John Smith', 'john@example.com', 'Hello World', 'This is a test email.')
      None
      """
      @app.task
      def send_email(recipient_name, recipient_email, subject, message):
          msg = Message(subject, sender='example@example.com', recipients=[recipient_email])
          msg.body = message
          mail.send(msg)
      return send_email
output:     @app.task
      def send_email(recipient_name, recipient_email, subject, message):
          msg = Message(subject, sender='example@example.com', recipients=[recipient_email])
          msg.body = message
          mail.send(msg)
      return send_email