static void Main(string[] args)
 {
     try
     {
         ProductMock prodmock = new ProductMock();
         prodmock.GetProductDetails();
         new ProductMock().DisplayDetails(prodmock);
     }
     catch (DataEntryException dee)
     {
         WriteLine($"user defined exception: {dee.Message}");
     }
     catch (Exception e)
     {
         WriteLine($"base exception: {e.Message}");
     }
     finally {
         ReadLine();
     }
 }
 public void DisplayDetails(ProductMock p)
 {
     WriteLine($"Product Id={p.ProductId}, Product Name:{p.ProductName}, Price:{p.Price}");
 }