def __init__(self, setup_graph=None, before_train=None, trigger=None,
                 after_train=None):
        """
        Each lambda takes ``self`` as the only argument.
        """

        self._cb_setup_graph = setup_graph
        self._cb_before_train = before_train
        self._cb_trigger = trigger
        self._cb_after_train = after_train

        Each lambda takes ``self`` as the only argument.
        
tensorpack/callbacks/base.py