les ur = ur { ur_reft = tx $ ur_reft ur }
  where
    tx r = {- traceFix ("killholes: r = " ++ showFix r) $ -} mapPredReft dropHoles r
    dropHoles    = pAnd . filter (not . isHole) . conjuncts

killHoles ur = ur { ur_reft = tx $ ur_reft ur }
  where
    tx r = {- traceFix ("killholes: r = " ++ showFix r) $ -} mapPredReft dropHoles r
    dropHoles    = pAnd . filter (not . isHole) . conjuncts
killHoles ur = ur { ur_reft = tx $ ur_reft ur }
  where
    tx r = {- traceFix ("killholes: r = " ++ showFix r) $ -} mapPredReft dropHoles r
    dropHoles    = pAnd . filter (not . isHole) . conjuncts