public void AddComment()
        {
            // Get a work item
            WorkItem wi = WitClient.GetWorkItemAsync(this.WorkItemsAdded.First()).Result;

            // Get the current last comment of the work item
            WorkItemComments comments = WitClient.GetCommentsAsync(wi.Id.Value).Result;
            var originalCommentCount  = comments.Count;

            // Create a JSON patch document with an entry updating System.History
            JsonPatchDocument patchDocument = new JsonPatchDocument
            {
                new JsonPatchOperation()
                {
                    Operation = Operation.Add,
                    Path      = "/fields/System.History",
                    Value     = "Added a comment"
                }
            };

            // Update the work item with the patch document
            var result = WitClient.UpdateWorkItemAsync(patchDocument, wi.Id.Value).Result;

            // Get the current last comment of the work item
            var updatedComments     = WitClient.GetCommentsAsync(result.Id.Value).Result;
            var updatedCommentCount = updatedComments.Count;

            // Show that the current last comment is different than the original last comment
            Console.WriteLine($"There were {originalCommentCount} comments");
            Console.WriteLine($"There are now {updatedCommentCount} comments");
            Console.WriteLine();
        }