class_docstr: Trigger invoked when specific value becomes best.
  
  Args:
      key (str): Key of value.
      compare (callable): Compare function which takes current best value and
          new value and returns whether new value is better than current
          best.
      trigger: Trigger that decides the comparison interval between current
          best value and new value. This must be a tuple in the form of
          ``<int>, 'epoch'`` or ``<int>, 'iteration'`` which is passed to
          :class:`~chainer.training.triggers.IntervalTrigger`.
class_docstr_tok: ["Trigger","invoked","when","specific","value","becomes","best",".","Args",":","key","(","str",")",":","Key","of","value",".","compare","(","callable",")",":","Compare","function","which","takes","current","best","value","and","new","value","and","returns","whether","new","value","is","better","than","current","best",".","trigger",":","Trigger","that","decides","the","comparison","interval","between","current","best","value","and","new","value",".","This","must","be","a","tuple","in","the","form","of","``","<","int",">",",","'epoch","'","``","or","``","<","int",">",",","'iteration","'","``","which","is","passed","to",":","class",":","`","~chainer.training.triggers.IntervalTrigger","`","."]
code: def __init__(self, key, compare, trigger=(1, "epoch")):
      self._key = key
      self._best_value = None
      self._interval_trigger = util.get_trigger(trigger)
      self._init_summary()
      self._compare = compare
  
file_path: chainer/chainer/training/triggers/minmax_value_trigger.py
imports: from chainer import reporter
  from chainer.training import util
label_desc: Use image node_id 1 to create a new BestValueTrigger object from inherited base classes: object with example: obj = BestValueTrigger(key, compare, trigger)