gistfile1.cs

public class Calculator
{
    public bool CanDivide(double left, double right)
    {
        return right != 0;
    }
 
    [Preview("CanDivide")]
    [AsyncAction(BlockInteraction = true)]
    public double Divide(double left, double right)
    {
        Thread.Sleep(3000);
        return left / right;
    }
}