public void ConfigureServices(IServiceCollection services)

{

    services.AddApiVersioning(options =>

    {

        // if we don't specify an api version, assume the default versioon is 1.0

        options.DefaultApiVersion = new ApiVersion(1, 0);

        // specify where to read the version number from

        options.ApiVersionReader

            = new MediaTypeApiVersionReader();

        // if api version is not specified assume default version to be the one we specified earlier

        options.AssumeDefaultVersionWhenUnspecified = true;

        // so that we can get an api version information in the responses

        options.ReportApiVersions = true;

        options.ApiVersionSelector

             = new CurrentImplementationApiVersionSelector(options);

    });

}