code: def crop_square(im, r, c, sz):
      '''
      crop image into a square of size sz,
      '''
      return im[r:r+sz, c:c+szf crop_square(im, r, c, sz):
      '''
      crop image into a square of size sz,
      '''
      return im[r:r+sz, c:c+sz]
docs: crop image into a square of size sz,