Solid from Surface using python?

Can anyone help me to create solid from top surface of ceiling using python?

Ts = HostObjectUtils.GetTopFaces(Ele_)
above method is returning a Reference.Can anyone guide me to understand what is a reference in Revit API context.
Once I get the top surface I can use
solid = Ts.Thicken(50,False) to create the solid.

Below code will work.
Ele_ = UnwrapElement(IN[0])
Element_Reference = HostObjectUtils.GetTopFaces(Ele_)

Element_ = doc.GetElement(Element_Reference[0])
Surface_R = Element_.GetGeometryObjectFromReference(Element_Reference[0])
Surface_D = Surface_R.ToProtoType()
Solid_ = Surface_D[0].Thicken(50,False)

Assign your output to the OUT variable.

OUT = Solid_