Get formula value from user string

Tried searching the forum, apologies if i missed it. Quick question: is there an easy way to get the value of a user string set through a formula?

What we get out is %<Area("3e7dd1d2-0642-4b8c-90eb-4811d5f8c1c5")>% where using a very bare bones conversion:

    foreach (var key in userStrings.AllKeys)
    {
      properties[key] = userStrings[key];
    }

You’ll need to use RhinoApp.ParseTextField to compute the function string results.

https://developer.rhino3d.com/api/rhinocommon/rhino.rhinoapp/parsetextfield