mapRegionB :: Region -> (Char -> Char) -> BufferM ()
mapRegionB r f = do
  text <- readRegionB r
  replaceRegionB r (R.map f text)

-- | Swap the content of two Regions
mapRegionB :: Region -> (Char -> Char) -> BufferM ()
mapRegionB r f = do
  text <- readRegionB r
  replaceRegionB r (R.map f text)

-- | Swap the content of two Regions
mapRegionB r f = do
  text <- readRegionB r
  replaceRegionB r (R.map f text)

-- | Swap the content of two Regions