The LOL Translator

[zivoni]

if FirstLetter == "a" or FirstLetter == "e" or FirstLetter == "i" or FirstLetter == "o" or FirstLetter == "u":

is same as

if FirstLetter in ['a', 'e', 'i', 'o', 'u']:

And you know that FirstLetter is a single character, so it is same as

if FirstLetter in "aeiou":

Its questionable which of last two versions is more readable ...