code: def checkerboard_level_set(image_shape, square_size=5):
      
  
      grid = np.ogrid[[slice(i) for i in image_shape]]
      grid = [(grid_i // square_size) & 1 for grid_i in grid]
  
      checkerboard = np.bitwise_xor.reduce(grid, axis=0)
      res = np.int8(checkerboard)
      return res
docs: Create a checkerboard level set with binary values.
  
      Parameters
      ----------
      image_shape : tuple of positive integers
          Shape of the image.
      square_size : int, optional
          Size of the squares of the checkerboard. It defaults to 5.
  
      Returns
      -------
      out : array with shape `image_shape`
          Binary level set of the checkerboard.
  
      See also
      --------
      circle_level_set