anchor.diff:      member this.UnregisterUncorrelated index =
           if index <> freeIndex then
               components.[index].RefCount <- dec components.[index].RefCount
  -            if components.[index].RefCount = 0 then freeList.AddToBack index
  +            if components.[index].RefCount = 0 then freeList.Add index |> ignore
           else freeIndex <- dec freeIndex
   
       type Ecs<'w when 'w :> Freezable> with
  
positive.code: open System.IO
  open System.Runtime.CompilerServices
  open System.Threading.Tasks
  open Nito.Collections
  open Prime
  
  /// A freezable type.
  
negative.code: 
      member this.RegisterUncorrelated comp =
          if freeList.Count > 0 then
              let index = Seq.head freeList
              let _ : bool = freeList.Remove index
              components.[index] <- comp
          elif freeIndex < components.Length then
              components.[freeIndex] <- comp
  