def __init__(self, regex='.*', collections=None):
        """
        Args:
            regex(str): same as in :class:`MapGradient`.
            collections (list[str]): list of collection names
        """
        super(SummaryGradient, self).__init__(self._mapper, regex)
        self._coll = collections

        Args:
            regex(str): same as in :class:`MapGradient`.
            collections (list[str]): list of collection names
        
tensorpack/tfutils/gradproc.py