RebarShape Issue

Hi,
I just started to learn python and Revit API and I just have my first problems.
I am trying to create a reinforcement in column. I want to use CreateRebarFromShape and collecting this shape from Revit is something I cannot do.

I have something like this:
aaa = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_RebarShape).WhereElementIsElementType().FirstElement()
This gives me Autodesk.Revit.DB.FamilySymbol not RebarShape. Can you explain why this works this way and how to get RebarShape from Revit or from this FamilySymbol?

Ɓukasz