input: Write a function to generate a random number between two given numbers. If the given numbers are invalid (e.g., min is greater than max), return None. Otherwise, return a random integer between the two numbers (inclusive).
  
  def random_number_generator(min, max):
      if min > max:
          return None
      return random.randint(min, max)
  
  assert random_number_generator(2, 5) in [2, 3, 4, 5]
  assert random_number_generator(5, 2) == None
  assert random_number_generator(-3, 0) in [-3, -2, -1, 0]
  assert random_number_generator(1, 1) == 1
output: def random_number_generator(min, max):
      if min > max:
          return None
      return random.randint(min, max)