input: Write a python function to generate a 3x3 matrix with random integers between 1 and 9.
  assert len(generate_matrix()) == 3 and all(len(row) == 3 for row in generate_matrix())
  assert all(1 <= num <= 9 for row in generate_matrix() for num in row)
  result = generate_matrix()
  print(result)
output: import random
  
  def generate_matrix():
      return [[random.randint(1, 9) for _ in range(3)] for _ in range(3)]