10-flagging-interface.cs

interface IService
{
    string GetData();
}

interface IHttpService : IService {}

class HttpService : IHttpService
{
    public string GetData() => "Data obtained via HTTP";
}

class LoggingService : IService
{
    private readonly IHttpService service;

    public LoggingService(IHttpService service)
    {
        this.service = service;
    }

    public string GetData()
    {
        // Logging done
        return service.GetData();
    }
}