= sc_scrut scrut `thenUs` \ (scrut_usg, scrut') ->
mapAndUnzipUs sc_alt alts `thenUs` \ (alts_usgs, alts') ->
returnUs (combineUsages alts_usgs `combineUsage` scrut_usg,
= sc_scrut scrut `thenUs` \ (scrut_usg, scrut') ->
mapAndUnzipUs sc_alt alts `thenUs` \ (alts_usgs, alts') ->
returnUs (combineUsages alts_usgs `combineUsage` scrut_usg,