anchor.diff:  // providers (event source names), and every time we pick up a message, we
   // push it to the returned IObservable.
   //
  -// This session is shared across all running azmon processes.
  +// This ETW session is shared across all running azmon processes. The Session
  +// instance returned will stop sending events when it is Dispose()d.
   let start name (names: string list) =
       let sess = createSession name
       enableProviders names sess
  
positive.code:     with
      interface System.IDisposable with
          member x.Dispose() =
              x.Subject.Dispose()
  
  let (|Null|Value|) (x: System.Nullable<_>) =
      // Apparently GetValueOrDefault is faster, and the Unchecked.defaultof<> cannot
  
negative.code: open Microsoft.Diagnostics.Tracing
  open Microsoft.Diagnostics.Tracing.Session
  open System.Reactive.Subjects
  
  // Problems:
  //* Tests are SUPER flaky
  