topIdLvl :: Id -> ThLevel
-- Globals may either be imported, or may be from an earlier "chunk"
-- (separated by declaration splices) of this module. The former
--- *can* be used inside a top-level splice, but the latter cannot.
+-- *can* be used inside a top-level splice, but the latter cannot.
-- Hence we give the former impLevel, but the latter topLevel
-- E.g. this is bad:
-- x = [| foo |]