Create a function that returns true if two strings share the same letter pattern, and false otherwise.
same_letter_pattern("ABAB", "CDCD") ➞ true
same_letter_pattern("ABCBA", "BCDCB") ➞ true
same_letter_pattern("FFGG", "CDCD") ➞ false
same_letter_pattern("FFFF", "ABCD") ➞ falseN/A