input: Write a function to generate random passwords that consist of 8 characters. The function should not take any input parameters and should return a string.
  assert generate_password() != generate_password()
  assert len(generate_password())==8
  expected = set(generate_password())
  assert (expected.issuperset(string.ascii_letters) and expected.issuperset(string.digits))
output: import random
  import string
  
  def generate_password():
      return ''.join(random.choices(string.ascii_letters + string.digits, k=8))