input: Write a function to generate a random password using a set of letters, numbers, and special characters given no input. The function should return a password of 8 characters randomly selected from the provided set.
  
  import random
  
  def generate_password():
      string = "abcdefghijklmnopqrstuvwxyz01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ!@#$%^&*()?"
      password = "".join(random.sample(string, 8))
      return password
  
  assert len(generate_password()) == 8
  assert any(char.isdigit() for char in generate_password())
  assert any(char.isupper() for char in generate_password())
  assert any(char.islower() for char in generate_password())
  assert any(char in "!@#$%^&*()?" for char in generate_password())
output: def generate_password():
      string = "abcdefghijklmnopqrstuvwxyz01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ!@#$%^&*()?"
      password = "".join(random.sample(string, 8))
      return password