input: Write a function to generate a random integer within the range [0, 9] using Python's random module. The function should return the generated integer.
  assert generate_random_number() in range(10)
  assert generate_random_number() in range(10)
  assert generate_random_number() in range(10)
  assert generate_random_number() in range(10)
  assert generate_random_number() in range(10)
output: import random
  
  def generate_random_number():
      return random.randint(0, 9)