class_docstr: Attributes:
      params (dict): Contains ``'epoch'`` and ``'steps_per_epoch'`` keys which are passed to the
          when training. Contains ``'steps'`` when evaluating. May contain other keys.
      model (Model): A reference to the :class:`~poutyne.Model` object which is using the callback.
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code: def __init__(self):
      self.model = None
      self.params = None
  
imports: from typing import Dict, Sequence
label_desc: Use image node_id 1 to create a new Callback object  with example: obj = Callback()