input: Write a python function to generate a list of 4 random integers between 0 and 9 and return the list.
  assert len(generate_random_numbers())==4
  assert all(0 <= x <= 9 for x in generate_random_numbers())
output: import random
  
  def generate_random_numbers():
      return [random.randint(0, 9) for _ in range(4)]