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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 create(cls):
 """Create a file instance. Note, object is only added to the database session. """

        obj = cls(
            id=uuid.uuid4(),
            writable=True,
            readable=False,
            size=0,
        )
        db.session.add(obj)
        return obj