+ # The `i`-th char after self (in code point)
+ #
+ # ~~~
+ # assert 'A' + 5 == 'F'
+ # ~~~
+ #
+ # Alias of `successor`.
+ fun +(i: Int): Char do return successor(i)
+
+ # The `i`-th char before self (in code point)
+ #
+ # ~~~
+ # assert 'F' - 5 == 'A'
+ # ~~~
+ #
+ # Alias of `predecessor`.
+ fun -(i: Int): Char do return predecessor(i)
+