code: def percent_black(image):
      n = np.prod(image.shape)
      k = sum(image < 0.5)
      return k * 100.0 / n
  
imports: import random
  from random import randint
  import numpy
  import cv2
label_desc: Use image node_id 8 for calling a global function with example usage: percent_black(image) and returns: unknown