To extract records that have multiple authors from a recordset, you need to perform the following steps:

1. Define the method to accept the original recordset:

    @api.model 
    def books_with_multiple_authors(self, all_books):

2. Define an inner predicate function:

    def predicate(book):
        if len(book.author_ids) > 1:
            return True
        return False

3. Call filter(), as follows:

 return all_books.filter(predicate)