input: Write a function to create a 3D numpy array and return its shape.
  assert create_3d_array().shape == (3, 3, 3)
  assert (create_3d_array() == numpy.array([[[0, 0, 0], [1, 1, 1], [2, 2, 2]],
                                            [[3, 3, 3], [4, 4, 4], [5, 5, 5]],
                                            [[6, 6, 6], [7, 7, 7], [8, 8, 8]]])).all()
output: import numpy as np
  
  def create_3d_array():
      array = np.array([[[i for _ in range(3)] for i in range(j*3, (j+1)*3)] for j in range(3)])
      return array