code: def shot_noise(x, severity=1):
    
    c = [60, 25, 12, 5, 3][severity - 1]
    x = np.array(x) / 255.
    x_clip = np.clip(np.random.poisson(x * c) / float(c), 0, 1) * 255
    return around_and_astype(x_clip)
docs: Shot noise corruption to images.
  
    Args:
      x: numpy array, uncorrupted image, assumed to have uint8 pixel in [0,255].
      severity: integer, severity of corruption.
  
    Returns:
      numpy array, image with uint8 pixels in [0,255]. Added shot noise.