code: def setUp(self):
      super(TestDecodingSegmentDefaultDuration, self).setUp()
      self.start = 1
      self.duration = None
      self.expected_duration = self.array_duration - self.start
  
imports: from __future__ import division
  from timeside.plugins.decoder.array import ArrayDecoder
  from unit_timeside import *
  import numpy
label_desc: Use image node_id 1 for calling the TestDecodingSegmentDefaultDuration obj's underlying member method code with example usage: obj.setUp() without return types