AbstractSubclasses.md

public class AfricanBird : Bird
{
    public override double GetSpeed()
    {
        // logic for African birds
    }
}

public class AmericanBird : Bird
{
    public override double GetSpeed()
    {
        // logic for American birds
    }
}

public class EuropeanBird : Bird
{
    public override double GetSpeed()
    {
        // logic for European birds
    }
}