input: 
  def encrypt(message: str, key: str) -> str:
      """ Takes a message and a key, encrypts the message using a simple encryption method.
      The encryption method adds the ASCII value of the first character of the key to each character of the message.
  
      >>> encrypt("Hello world!", "secret")
      'Tqxx{,zyxs!'
      """
  
output:     encrypted_message = ""
      key_value = ord(key[0])
      for char in message:
          encrypted_message += chr(ord(char) + key_value)
      return encrypted_message