idref (Ast.Cast (k ~context ty, k ~context s))
| NCic.LetIn (n,s,ty,t) ->
idref (Ast.LetIn ((Ast.Ident (n,None), Some (k ~context s)), k ~context
idref (Ast.Cast (k ~context ty, k ~context s))
| NCic.LetIn (n,s,ty,t) ->
idref (Ast.LetIn ((Ast.Ident (n,None), Some (k ~context s)), k ~context