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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def finish(cls, document):
 """ Take a assembled document and convert all assembled values to finished values. """

        target_document = {}
        document_copy = {}
        for field_name, value in document.items():
            maker = cls._instructions[field_name]
            target_document = document.copy()
            with maker.target(target_document):
                document_copy[field_name] = maker(value)
                target_document[field_name] = document_copy[field_name]
        return document_copy