ValidateCreateAnnotationTypeCommand(CreateAnnotationTypeCommand cmd)
 => from x in ValidateNonNull(cmd)
 from y in (ValidateEntityTypeName(x.Name), ValidateEntityTypeRoot(x.Root))
 public Try <Validation <Error, AnnotationTypeDto> > Execute(CreateAnnotationTypeCommand cmd)
 => ()
 => from x in ValidateCreateAnnotationTypeCommand(cmd)
 let y                 = x.ToAnnotationType()
                 let z = repository.Create(y)
                         select z.ToAnnotationTypeDto();