GraphQL with .NET Core, C#

Schema.cs

namespace Example
{
    public class RootQueryType
    {
        public Func<string> Hello { get; set; } = () => "world";
    }

    public class Schema
    {
        public RootQueryType Query { get; set; }
    }
}

Startup.cs

namespace Example
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            app.UseGraphQL<Schema>();
        }

        public static void Main()
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseStartup<Startup>()
                .Build();

            host.Run();
        }
    }
}

i can't finde the useGraphQL in the package mentioned but im using this one: https://github.com/wesamco/ASP.Net-Core-GraphQL-Middleware