input: Write a function to generate a random password of length 8, which consists of alphanumeric characters and at least one special character.
  
  assert generate_password()!=generate_password()
  assert len(generate_password())==8
  assert any([char in string.punctuation for char in generate_password()])==True
output: import random
  import string
  
  def generate_password():
      password = ''.join(random.choices(string.ascii_letters + string.digits, k=7))
      password += random.choice(string.punctuation)
      return ''.join(random.sample(password, len(password)))