input: Write a function to generate a random password consisting of 8 characters. The password should include both letters (uppercase and lowercase) and digits. If the input is not applicable, simply return the generated password.
  assert generate_password()!=generate_password()
  assert len(generate_password())==8
output: import random
  import string
  
  def generate_password():
      characters = string.ascii_letters + string.digits
      return ''.join(random.choice(characters) for _ in range(8))