code: def box_extent(box):
      n = len(box) // 2
      return box[n:] - box[:n]
  
imports: from nose_utils import assert_raises
  import nvidia.dali
  import nvidia.dali.fn
  import nvidia.dali.ops
  import numpy
  import scipy.ndimage
  import scipy.ndimage.measurements
  import random
  from test_utils import check_batch, np_type_to_dali
  from nose.tools import nottest
  from nose.plugins.attrib import attr
label_desc: Use image node_id 6 for calling a global function with example usage: box_extent(box) and returns: unknown