anchor.diff:      let chars = ArrayPool<char>.Shared.Rent sb.Length
       sb.CopyTo(0, chars, 0, sb.Length)
       let result = Encoding.UTF8.GetBytes(chars, 0, sb.Length)
  -    StringBuilderPool.Return sb
  +    StringBuilderPool.Release sb
       ArrayPool<char>.Shared.Return chars
       result
   
  
positive.code: let private MaximumLifetime = TimeSpan.FromMinutes 10.0
  
  type public StringBuilderPool =
      [<DefaultValue; ThreadStatic>]
      static val mutable private alwaysCreateNew : bool
  
      [<DefaultValue; ThreadStatic>]
      static val mutable private instance : StringBuilder
  
negative.code:     [<DefaultValue; ThreadStatic>]
      static val mutable private created : DateTimeOffset
  
      static member public IsEnabled
          with get ()   = StringBuilderPool.isEnabled
          and  set flag = StringBuilderPool.isEnabled <- flag
  
      static member internal Rent () =
          match StringBuilderPool.IsEnabled with
          | false -> new StringBuilder(MinimumCapacity)
          | true  ->
              let lifetime = DateTimeOffset.Now - StringBuilderPool.created
              let expired  = lifetime > MaximumLifetime
              let sb       = StringBuilderPool.instance
  