public RelaySimpleCommand(Action execute, Func<bool> canExecute = null, Action<IList<ValidationError>> onValidationError = null, Action<Exception> onExecutionError = null)
{
execute.ThrowExceptionIfArgumentIsNull("execute");
this.execute = execute;
this.canExecute = canExecute;
this.onValidationError = onValidationError;
this.onExecutionError = onExecutionError;
}