public void Test()
{
//Covariance<Base> coB = new CoContraVarianceCollection();
//Covariance<Derived> coD = coB;
Covariance <Derived> coD = new CoContraVariance();
Covariance <Base> coB = coD;
//Contravariance<Derived> contraD = new CoContraVarianceCollection();
//Contravariance<Base> contraB = contraD;
Contravariance <Base> contraB = new CoContraVariance();
Contravariance <Derived> contraD = contraB;
}
public static CoContraVariance GetVariances() => _coll ?? (_coll = new CoContraVariance());