module.cs

public class Module : NancyModule
{
    private readonly IMediator _mediator;

    public Module(IMediator mediator)
    {
        _mediator = mediator;

        Put["/demo/changepricinglevel/{MessageId:Guid}"] = ChangePricingLevel;
    }

    private dynamic ChangePricingLevel(dynamic o)
    {
        var cmd = this.Bind<ChangeCustomerPricingLevel>();
        var envelop = new Envelope<ChangeCustomerPricingLevel>((Guid)o.MessageId, cmd);
        _mediator.SendAsync(envelop);

        return HttpStatusCode.NoContent;
    }
}