+tcLookupClassByKey_maybe :: Unique -> NF_TcM s (Maybe Class)
+tcLookupClassByKey_maybe key
+ = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve gtvs) ->
+ case lookupUFM_Directly te key of
+ Just (_, _, AClass cl) -> returnNF_Tc (Just cl)
+ other -> returnNF_Tc Nothing
+