"hello".tr('el', 'ip')      #=> "hippo"
"hello".tr('aeiou', '*')    #=> "h*ll*"
"hello".tr('aeiou', 'AA*')  #=> "hAll*"

ALPHABETS = list(chr(x) for x in range(ord('a'), ord('z')+1))
TRANSLATION_TABLE = str.maketrans(''.join(ALPHABETS), ''.join(reversed(ALPHABETS)))
[ch.translate(TRANSLATION_TABLE) for ch in 'aeiou']