code: def testScheduledSampleProbMid(self):
      _, _, ss_out = self._run_scheduled_sample_func(
          common_video.scheduled_sample_prob, 0.5, 1000
      )
      positive_count = np.sum(ss_out > 0)
      self.assertAlmostEqual(positive_count / 1000.0, 0.5, places=1)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  from tensor2tensor.layers import common_video
  from tensor2tensor.utils import test_utils
  import tensorflow.compat.v1
label_desc: Use image node_id 3 for calling the CommonVideoTest obj's underlying member method code with example usage: obj.testScheduledSampleProbMid() without return types