: ceasar(c, key)
c dup isLetter ifFalse: [ return ]
isUpper ifTrue: [ 'A' ] else: [ 'a' ] c key + over - 26 mod + ;
: cipherE(s, key) s map(#[ key ceasar ]) charsAsString ;
: cipherD(s, key) cipherE(s, 26 key - ) ;