public static Validation <Error, DocumentUpdatedEvent> Create(Guid documentId, string number,
                                                               string description) =>
 DocumentNumber.Create(number)
 .Bind(num => DocumentDescription.Create(description)
       .Map(desc => new DocumentUpdatedEvent(new DocumentId(documentId), num, desc, DateTime.UtcNow)));
 private static Validation <Error, Document> CreateDocument(string number = "1234", string description = "Test")
 {
     return(DocumentNumber.Create(number)
            .Bind(num => DocumentDescription.Create(description)
                  .Map(desc => new Document(new DocumentId(Guid.Empty), new UserId(Guid.Empty), num, desc))));
 }