input: Write a python function to implement a Caesar cipher for uppercase letters.
  assert caesarCipher("ABC", 1) == "BCD"
  assert caesarCipher("XYZ", 3) == "ABC"
  assert caesarCipher("HELLO", 5) == "MJQQT"
output: def caesarCipher(text, shift):
      result = ""
      for char in text:
          if char.isupper():
              result += chr((ord(char) - ord('A') + shift) % 26 + ord('A'))
          else:
              result += char
      return result