This is a fully implemented example of ICollection.

Program.cs can be more interactive, but I wanted to show how to use the interface. I have researched MSDN documentation, books on C#, Stackoverflow, Github, c-sharpcorner and many more sources - examples were not complete (examples used "NotImplementedException").

If you feel you can add something, please go ahead.

I have used a few C# 6 features, like => operator, immutable properties, expression-bodied function members,

using static directive, string interpolation, auto-property initializers, nameof