input: Write a function to generate a random password of length 8, which consists of alphanumeric characters and at least one special character. If the generated password does not contain at least one special character, regenerate it until it does. If the password contains at least one special character, return it.
  
  assert generate_password() != generate_password()
  assert len(generate_password()) == 8
  assert any([char in string.punctuation for char in generate_password()])
output: import random
  import string
  
  def generate_password():
      while True:
          password = ''.join(random.choices(string.ascii_letters + string.digits + string.punctuation, k=8))
          if any(char in string.punctuation for char in password):
              return password