class_docstr: This class consists of network variables and operations at each iteration.
  It is generated by the application engine but can be modified by the
  application as well.
class_docstr_tok: ["This","class","consists","of","network","variables","and","operations","at","each","iteration",".","It","is","generated","by","the","application","engine","but","can","be","modified","by","the","application","as","well","."]
docstr: measuring time used
  from setting self.current_iter to setting self.current_iter_output
  
  :return: time duration of an iteration
docstr_tok: ["measuring","time","used","from","setting","self.current_iter","to","setting","self.current_iter_output",":","return",":","time","duration","of","an","iteration"]
code: def iter_duration(self):
      """
      measuring time used
      from setting self.current_iter to setting self.current_iter_output
  
      :return: time duration of an iteration
      """
  
      current_toc = max(self._current_iter_toc, self._current_iter_tic)
      return current_toc - self._current_iter_tic
  
imports: import itertools
  import time
  from niftynet.engine.application_variables import CONSOLE, TF_SUMMARIES
  from niftynet.engine.signal import TRAIN, VALID, INFER
  from niftynet.utilities.util_common import look_up_operations
label_desc: Use image node_id 16 for calling the IterationMessage obj's underlying member method code with example usage: obj.iter_duration() and returns: unknown