Cannot apply indexing with [] to an expression of type 'method group' SinglePageApp1. Get["/"] Nancy

I try to make a class with NancyModules and GET string on URL but method 'Get' tells that:

"Error CS0021 Cannot apply indexing with [] to an expression of type 'method group' ...."

My Code:

using System; using System.Collections.Generic; using System.Linq;
using System.Web; using Nancy; using System.Text;

namespace SinglePageApp1 {
    public class BloodPresureNancy : NancyModule
    {
        public BloodPresureNancy()
        {

            // Get dasn't work
            Get["/"] = _ => "Heloooo";
        }
    } 
}

I add references: Nancy, Nancy.Hosting.asp and it isn't working.