The commented part is not complete.
It must be:
public override string ToString()
{
string result = string.Format("{0} of {1}", this.value, this.suit);
return result;
}
You missed the first line.
The method ToString() is used to replace the standard ToString() method
that every object has in order to return a custom string.
Background:
Every class in C# is automatically derived from the object class.
ToString() is a method of the object class.
Please read this:
https://msdn.microsoft.com/en-us/library/system.object.tostring%28v=vs.110%29.aspx[
^]
A class therefore automatically has a ToString() method.
When you override the ToString() method
you can return a custom string.