F caesar(string, =key, decode = 0B)
   I decode
      key = 26 - key

   V r = ‘ ’ * string.len
   L(c) string
      r[L.index] = S c
                      ‘a’..‘z’
                         Char(code' (c.code - ‘a’.code + key) % 26 + ‘a’.code)
                      ‘A’..‘Z’
                         Char(code' (c.code - ‘A’.code + key) % 26 + ‘A’.code)
                      E
                         c
   R r

V msg = ‘The quick brown fox jumped over the lazy dogs’
print(msg)
V enc = caesar(msg, 11)
print(enc)
print(caesar(enc, 11, decode' 1B))