Validation using https://fluentvalidation.codeplex.com/wikipage?title=mvc in WPF and Caliburn Micro

ValidationHelper.cs

namespace {Product}.Infrastructure.Framework {
	using FluentValidation;
	using FluentValidation.Results;
	using System;
	using System.Text;
	public static class ValidationHelper {
		public static ValidationResult Validate<T, K>(K entity)
			where T : IValidator<K>, new()
			where K : class {
			IValidator<K> __Validator = new T();
			return __Validator.Validate(entity);
		}
		public static string GetError(ValidationResult result) {
			var __ValidationErrors = new StringBuilder();
			foreach (var failure in result.Errors) {
				__ValidationErrors.Append(failure.ErrorMessage);
				__ValidationErrors.Append(Environment.NewLine);
			}
			return __ValidationErrors.ToString();
		}
	}
}

ValidationScreen.cs

namespace {Product}.Infrastructure.Framework {
	using Caliburn.Micro;
	using FluentValidation;
	using FluentValidation.Results;
	using System.ComponentModel;
	using System.Linq;

	public class ValidationScreen<TValidator, TViewModel> : Screen, IDataErrorInfo
		where TValidator : IValidator<TViewModel>, new()
		where TViewModel : ValidationScreen<TValidator, TViewModel> {
		bool _IsDirty = false;
		public bool IsDirty {
			get { return _IsDirty; }
			protected set {
				_IsDirty = value;
				NotifyOfPropertyChange(() => IsDirty);
			}
		}
		public bool IsValid {
			get { return SelfValidate().IsValid; }
		}
		public ValidationResult SelfValidate() {
			TViewModel viewModel = (TViewModel)this;
			return ValidationHelper.Validate<TValidator, TViewModel>(viewModel);
		}

		public string Error {
			get { return ValidationHelper.GetError(SelfValidate()); }
		}

		public string this[string columnName] {
			get {
				var validationResults = SelfValidate();
				if (validationResults == null) {
					return string.Empty;
				}
				var columnResult = validationResults.Errors.FirstOrDefault<ValidationFailure>(x => string.Compare(x.PropertyName, columnName, true) == 0);
				return columnResult != null ? columnResult.ErrorMessage : string.Empty;
			}
		}
	}
}