I feel the same. Unorder (like in dict or set) is not a feature, I guess. Set is useful for it ensures uniqueness of items, not because of unorder. A kind of "unique-item" sequence would do as well.
Unorder is rather a consequence of hash implementation for performance, but I cannot find any use case where it would be a useful feature. Examples welcome.
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Daniel Stutzbach, Ph.D.
President, Stutzbach Enterprises, LLC