anchor.diff:  
               // new component; use a pre-allocated component
               if preDeque.Count > 0 then
  -                let index = preDeque.RemoveFromFront ()
  +                let index = Seq.head preDeque
  +                let _ : bool = preDeque.Remove index
                   correlations.Add (entityId, index)
                   components.Array.[index] <- comp
                   let comp = &components.Array.[index]
  
positive.code: 
              // new component; use a pre-allocated component
              if this.PreDeque.Count > 0 then
                  let index = this.PreDeque.RemoveFromFront ()
                  this.Correlations.Add (entityId, index)
                  let mutable comp = comp.Junction systems entityId ecs
                  comp.RefCount <- inc comp.RefCount
  
negative.code:                     if i = 0 then
                          comp.RefCount <- inc comp.RefCount
                          this.Correlations.Add (entityId, index)
                      else this.PreDeque.Add index |> ignore
                      this.Components.Array.[index] <- comp
  
                  // fin
  