chore: remove commented-out code

Author: AhmadHmedann

Sprint-2/improve_with_precomputing/count_letters/count_letters.py

@@ -1,18 +1,3 @@
-# def count_letters(s: str) -> int:
-#     """
-#     count_letters returns the number of letters which only occur in upper case in the passed string.
-#     """
-#     only_upper = set()
-#     for letter in s:
-#         if is_upper_case(letter):
-#             if letter.lower() not in s:
-#                 only_upper.add(letter)
-#     return len(only_upper)
-
-
-# def is_upper_case(letter: str) -> bool:
-#     return letter == letter.upper()
-
 def count_letters(s: str) -> int:
     """
     count_letters returns the number of letters which only occur in upper case in the passed string.