input: Write a function that takes a message and a key as inputs and encrypts the message by adding the ASCII value of the first character of the key to each character in the message. Return the encrypted message as a string.
  
  assert encrypt("Hello world!", "secret")=="Tqxx{,|_rx1"
output: def encrypt(message, key):
      encrypted_message = ""
      key_value = ord(key[0])
      for char in message:
          encrypted_message += chr(ord(char) + key_value)
      return encrypted_message