         // No op.
     }
 
+    // MARK: - Cancellation
+
     /**
      Cancel the operation with an error.
 

        get {
            var _dependencies = super.dependencies
            guard let
                waiter = waitForDependenciesOperation,
                index = _dependencies.indexOf(waiter) else {
                    return _dependencies
            }


        _internalErrors += errors
        cancel()
    }

    public override func cancel() {
        if !finished {
