code: def setUp(self):
      self.bbox = np.zeros((0, 4))
  
imports: import unittest
  import numpy
  from chainer.backends import cuda
  from chainer import testing
  from chainer.testing import attr
  from chainercv.utils import generate_random_bbox
  from chainercv.utils import non_maximum_suppression
label_desc: Use image node_id 1 for calling the TestNonMaximumSuppressionZeroLengthBbox obj's underlying member method code with example usage: obj.setUp() without return types