groupCoord :: CoreId -> CoreCoords
groupCoord coreId
    | isValidCoreId coreId = coreId `divMod` 4
    | otherwise = error $ "invalid core id: " ++ show coreId
groupCoord :: CoreId -> CoreCoords
groupCoord coreId
    | isValidCoreId coreId = coreId `divMod` 4
    | otherwise = error $ "invalid core id: " ++ show coreId
groupCoord coreId
    | isValidCoreId coreId = coreId `divMod` 4
    | otherwise = error $ "invalid core id: " ++ show coreId