input: 
  def encrypt(message: str, key: str) -> str:
      """
      Encrypt a message using a key by adding the ASCII value of the first character of the key
      to each character in the message. Convert the result back to a character and concatenate
      all characters to form the encrypted message.
      >>> encrypt("Hello world!", "secret")
      '\\x83\\x88\\x8b\\x8c\\x8c \\x91\\x8f\\x8b\\x8c\\x9f'
      """
      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