I was just reading a developer question who asked something like

Why is this an error "ListBox1.ItemsCount"

The obvious response is a typo, missing period, forgot the period between Items and Count. But then what if it was not a mistake? Suppose they have an extension method?

Code:
   <Runtime.CompilerServices.Extension()> _
   Public Function ListCount(ByVal sender As ListBox) As Int32
      Return sender.Items.Count
   End Function
Reminds me back in the day when developers didn't include the proper import statements.

Any ways something to think about when recieving code from an outside source. Of course when sending code do not forget to send the extensions, it can be easy to forget if say they are linked to the code and not physically in the project folder or sub-folders.