; pprPanic "checkFactMatch"
(f4sep [text (fact_name fact), text "at id" <+> ppr id,
text "changed from", nest 4 (ppr old_a), text "to",
; pprPanic "checkFactMatch"
(f4sep [text (fact_name fact), text "at id" <+> ppr id,
text "changed from", nest 4 (ppr old_a), text "to",