It's not so difficult. It's just covariance and contravariance. C# has long solved this issue. https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/

It's not so difficult. It's just covariance and contravariance. C# has long solved this issue. https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/covariance-contravariance/ https://docs.microsoft.com/en-us/dotnet/csharp/programming-g...