class_docstr: Trigger based on a fixed interval.
  
  This trigger accepts iterations divided by a given interval. There are two
  ways to specify the interval: per iterations and epochs. `Iteration` means
  the number of updates, while `epoch` means the number of sweeps over the
  training dataset. Fractional values are allowed if the interval is a
  number of epochs; the trigger uses the `iteration` and `epoch_detail`
  attributes defined by the updater.
  
  For the description of triggers, see :func:`~chainer.training.get_trigger`.
  
  Args:
      period (int or float): Length of the interval. Must be an integer if
          unit is ``'iteration'``.
      unit (str): Unit of the length specified by ``period``. It must be
          either ``'iteration'`` or ``'epoch'``.
code: def get_training_length(self):
      return (self.period, self.unit)
  
file_path: chainer/chainer/training/triggers/interval_trigger.py
imports: import warnings
label_desc: Use image node_id 4 for calling the IntervalTrigger obj's underlying member method code with example usage: obj.get_training_length() and returns: self,  self