Question about .netfiddle

at this site...
https://dotnetfiddle.net

select Project Type "Nancy"

I am not familiar with this structure:

      public class CustomerModule : NancyModule
      {
            public CustomerModule()
            {
                  // index is an entry point
                  Get["/index"] = parameters =>
                  {
                        var customers = GetCustomers();
                        return View[customers];
                  };
                  
                  Post["/add"] = parameters =>{
                        var customer = this.Bind<Customer>();

                        // lets validate it
                        var result = this.Validate<Customer>(customer);
                        if (!result.IsValid)
                        {
                              return RenderErrorView(result);
                        }

                        var customers = GetCustomers();
                        customers.Add(customer);
                        return View[customers];
                  };


Is this the non-MVC way of dealing with Get and Post? What would you call this paradigm?

Please explain the "/index" and "/add"

Thanks