input: Write a python function to implement a Caesar cipher.
  assert caesar_cipher("Caesar Cipher", 3) == "Fdhvdu Flskhu"
  assert caesar_cipher("Hello World", 5) == "Mjqqt Btwqi"
  assert caesar_cipher("Python", 2) == "Ravjqp"
output: def caesar_cipher(text, shift):
      result = ""
      for char in text:
          if char.isalpha():
              shift_base = 65 if char.isupper() else 97
              result += chr((ord(char) - shift_base + shift) % 26 + shift_base)
          else:
              result += char
      return result