counts' :: Int -> NominalDiffTime -> [(NominalDiffTime, StartEnd)]
        -> [(TSInterval, Int)]
counts' acc time ((now, pos):[]) = assert (acc == 1 && pos == End) $
  if now == time then [] else [((time, now), acc)]
counts' :: Int -> NominalDiffTime -> [(NominalDiffTime, StartEnd)]
        -> [(TSInterval, Int)]
counts' acc time ((now, pos):[]) = assert (acc == 1 && pos == End) $
  if now == time then [] else [((time, now), acc)]
counts' acc time ((now, pos):[]) = assert (acc == 1 && pos == End) $
  if now == time then [] else [((time, now), acc)]