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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 delete_marked_communities():
 """Delete communities after holdout time."""

    # TODO: Delete the community ID from all records metadata first
    raise NotImplementedError()
    Community.query.filter_by(
        Community.delete_time > datetime.utcnow()).delete()
    db.session.commit()