I have been trying to migrate some of the VSTA functionality to the Add-In Framework for Visual Studio 2017 in Zenon 7.60 but I am not sure how to do this.
I was looking for the same functionality as it was avaliable in the VSTA to access, read/write by variable name like this:

this.Variables().Item("VariableName").set_Value(vindex, value);

When I try to implement the same functionality in the Add-In Framework using Developer Tools for VS 2017, I cannot find the "Item" object like the one in the VSTA.
I'm using the IProject context from the Run or Start methods... 

IVariablesCollection zVariables = context.VariablesCollection;

And then i vould like to get the Item by the variable name... zVariables.Item("VariableName");... 
But there is no option to address the variable item by its name. The only method I can see is GetItemById which is not relevant for my use case...
I also went over all of the examples provided on the github repositories, but I don't find any relevant information about this.

Can someone please explain what I'm doing wrong... thank you.