inner contexts when reporting errors, else we get
--     Unexpected transform statement
--     in a transformed branch of
--          transformed branch of
--          transformed branch of monad comprehension
pprStmtContext (ParStmtCtxt c)
 | opt_PprStyle_Debug = sep [text "parallel branch of", pprAStmtContext c]
 | otherwise          = pprStmtContext c
pprStmtCont
pprStmtContext (ParStmtCtxt c)
 | opt_PprStyle_Debug = sep [text "parallel branch of", pprAStmtContext c]
 | otherwise          = pprStmtContext c
pprStmtContext (ParStmtCtxt c)
 | opt_PprStyle_Debug = sep [text "parallel branch of", pprAStmtContext c]
 | otherwise          = pprStmtContext c