using System;

public class RestResponse { }
public class RestResponse<T> : RestResponse { public T Data { get; set; } }

public static class Client
{
	public static RestResponse Execute()
	{
		return new RestResponse();
	}
	
	public static RestResponse<T> Execute<T>()
	{
		return new RestResponse<T>();
	}
}

public class Test
{
	public static void PerformApiCall(Func<RestResponse> method)
	{
		PerformRequestWithChecks<RestResponse>(method);
	}
	
	public static T PerformApiCall<T>(Func<RestResponse<T>> method)
	{
		var response = PerformRequestWithChecks<RestResponse<T>>(method);
		return response.Data;
	}
	
	private static T PerformRequestWithChecks<T>(Func<T> method) where T : RestResponse
	{
		var response = method();
		// Handle errors...
		return response;
	}
	
	public static void Main()
	{
		// Notice, returns a value
		var data = PerformApiCall(() => Client.Execute<int>());
		
		// Notice, is the empty version (has no .Data)
		PerformApiCall(() => Client.Execute());
	}
}