You have already seen the way of adding custom code to reports and you may have already experienced the issues with it such as:
With this recipe, we can overcome it by making an assembly that contains all required functions and use it with the report rather repeating it in every report.
In order to make an assembly with all required functions, you need to create a .NET class library using one of .NET languages. Yes, it is not limited to Vb.NET. Let's make one using C#.NET language.
Follow these steps for creating a class library: