class_docstr: This class handles iteration events to start/stop samplers' threads.
code: def __init__(self, **_unused):
      # SESS_STARTED.connect(self.start_sampler_threads)
      SESS_FINISHED.connect(self.stop_sampler_threads)
  
imports: import tensorflow
  from niftynet.engine.signal import SESS_FINISHED
  from niftynet.utilities.util_common import traverse_nested
label_desc: Use image node_id 1 to create a new SamplerThreading object from inherited base classes: object with example: obj = SamplerThreading()