@django.dispatch.receiver(post_delete, sender=Book)
def _remove_book_from_index_handler(sender, instance, **kwargs):
""" remove the book from search index, when it is deleted."""
@django.dispatch.receiver(post_delete, sender=Book)
def _remove_book_from_index_handler(sender, instance, **kwargs):
""" remove the book from search index, when it is deleted."""