unEsc :: String -> String
unEsc s = let m = Map.fromList $ map (\ (a, b) -> (b, a)) escMap
  in case s of
  "" -> ""
  'X' : c : r -> Map.findWithDefault c c m : unEsc r
  c : r -> c : unEsc r
unEsc :: String -> String
unEsc s = let m = Map.fromList $ map (\ (a, b) -> (b, a)) escMap
  in case s of
  "" -> ""
  'X' : c : r -> Map.findWithDefault c c m : unEsc r
  c : r -> c : unEsc r
unEsc s = let m = Map.fromList $ map (\ (a, b) -> (b, a)) escMap
  in case s of
  "" -> ""
  'X' : c : r -> Map.findWithDefault c c m : unEsc r
  c : r -> c : unEsc r