input: Write a function to pad a 3D numpy array with zeros along its first two axes.
  assert np.array_equal(pad_3d_array(np.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]])), 
                        np.array([[[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]],
                                  [[0, 0, 0], [1, 2, 3], [4, 5, 6], [0, 0, 0]],
                                  [[0, 0, 0], [7, 8, 9], [10, 11, 12], [0, 0, 0]],
                                  [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]]]))
  assert np.array_equal(pad_3d_array(np.array([[[1], [2]], [[3], [4]]])), 
                        np.array([[[0], [0], [0], [0]],
                                  [[0], [1], [2], [0]],
                                  [[0], [3], [4], [0]],
                                  [[0], [0], [0], [0]]]))
output: import numpy as np
  
  def pad_3d_array(array):
      padded_array = np.pad(array, pad_width=((1, 1), (1, 1), (0, 0)), mode='constant', constant_values=0)
      return padded_array