input: Write a python function to encrypt a given message using AES encryption with a PBKDF2-derived key.
  assert encrypt_message("This is an example") != "This is an example"
  assert isinstance(encrypt_message("Hello World"), bytes)
  assert len(encrypt_message("Another Test")) > 0
output: def encrypt_message(message):
      from Crypto.Cipher import AES
      from Crypto.Protocol.KDF import PBKDF2
      from Crypto.Random import get_random_bytes
      import base64
  
      password = b'secret_password'
      salt = get_random_bytes(16)
      key = PBKDF2(password, salt, dkLen=32)
      
      cipher = AES.new(key, AES.MODE_GCM)
      nonce = cipher.nonce
      ciphertext, tag = cipher.encrypt_and_digest(message.encode('utf-8'))
      
      encrypted_data = base64.b64encode(salt + nonce + tag + ciphertext)
      return encrypted_data