[Dune] ID for an interface

[Benjamin Faigle]

Hello Duners,

if i understood it right, the method
	grid.localIdSet().id(const EntityType &e)
should return a unique ID for every sort of entities, be it elements, 
vertices or intersections. It works out pretty well with elements, as 
shown for example in the Dune Grid Howto
	IdType idf = idset.id (* ep );

However, if I try the same with an *intersection, I get the error message:
...dune-grid/dune/grid/common/indexidset.hh:394:43: error: ‘codimension’ 
is not a member of ‘Dune::IntersectionIterator<const Dune::UGGrid<2>, 
Dune::UGGridLeafIntersectionIterator, Dune::UGGridLeafIntersection>’

I am using dune 2.0.
I am sorry if it is just an incredibly silly question, and many thanks 
for your help,

greetings,

Benjamin