code: def flatten(list_of_lists):
      return [item for sublist in list_of_lists for item in sublist]
  
imports: import os
  import io
  import typing
  import hashlib
  import urllib.request
  import urllib.parse
  import cv2
  import imgaug
  import numpy
  import validators
  import typing_extensions
  import matplotlib.pyplot
  from shapely import geometry
  from scipy import spatial
label_desc: Use image node_id 4 for calling a global function with example usage: flatten(list_of_lists) and returns: unknown