| 1234567891011121314 | from typing import Optionalfrom clean_python import InMemoryGatewayfrom clean_python import Managefrom .domain import Bookfrom .domain import BookRepositoryclass ManageBook(Manage[Book]):    def __init__(self, repo: Optional[BookRepository] = None):        if repo is None:            repo = BookRepository(InMemoryGateway([]))        self.repo = repo
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