input: from typing import Tuple
  
  def encrypt(message: str, key: str) -> str:
      """ Encrypt a message using a key by shifting each character in the message 
      by the unicode value of the first character of the key. 
      >>> encrypt("Hello world!", "secret")
      '\\x82ììì úø®û«'
      >>> encrypt("", "key")
      ''
      >>> encrypt("A", "A")
      'B'
      """
      encrypted_msg = ""
      for char in message:
          encrypted_msg += chr(ord(char) + ord(key[0]))
      return encrypted_msg
output:     encrypted_msg = ""
      for char in message:
          encrypted_msg += chr(ord(char) + ord(key[0]))
      return encrypted_msg