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Predicate pengine_unregister/1
 pengine_unregister(+Id)[private]
Called by the pengine thread destruction. If we are a remote pengine thread, our URL equals http and the queue is the message queue used to send events to the HTTP workers.
 pengine_register_local(+Id, +Thread, +Queue, +URL, +App, +Destroy) is det[private]
 pengine_register_remote(+Id, +URL, +Queue, +App, +Destroy) is det[private]
 pengine_unregister(+Id) is det[private]