anchor.diff:     * event loop and shut down the isolate.
      *
      * This call requires the [terminateCapability] for the isolate.
  -   * If the capability is not correct, no change is made.
  +   * If the capability absent or wrong, no change is made.
      *
      * Since isolates run concurrently, it's possible for it to exit due to an
      * error before errors are set non-fatal.
  
positive.code:    * When the isolate receives the pause command, it stops
     * processing events from the event loop queue.
     * It may still add new events to the queue in response to, e.g., timers
     * or receive-port messages. When the isolate is resumed, it handles
     * the already enqueued events.
     *
     * The pause request is sent through the isolate's command port,
     * which bypasses the receiving isolate's event loop.
     * The pause takes effect when it is received, pausing the event loop
     * as it is at that time.
     *
     * If [resumeCapability] is provided, it is used to identity the pause,
     * and must be used again to end the pause using [resume].
     * Otherwise a new resume capability is created and returned.
     *
     * If an isolate is paused more than once using the same capability,
     * only one resume with that capability is needed to end the pause.
  
negative.code:   /**
     * Capability granting the ability to terminate the isolate.
     *
     * This capability is required by [kill] and [setErrorsFatal].
     * If the capability is `null`, or if it is not the correct termination
     * capability of the isolate identified by [controlPort],
     * then calls to those methods will have no effect.
     */
    final Capability terminateCapability;
  
  