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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, bucket, key, value):
 """Create a new tag for bucket."""

        with db.session.begin_nested():
            obj = cls(
                bucket_id=as_bucket_id(bucket),
                key=key,
                value=value
            )
            db.session.add(obj)
        return obj