https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutablequeue.dequeue?view=dotnet-uwp-10.0&viewFallbackFrom=net-10.0
ImmutableQueue.DequeueT(IImmutableQueueT, T) Method (System.Collections.Immutable) | Microsoft...
Removes the item at the beginning of the immutable queue, and returns the new queue.
methodsystemcollectionsimmutablemicrosoft