def __init__(self, sdat):
self._isteps = {}<EOL>self._all_isteps_known = False<EOL>super().__init__(sdat)<EOL>
Initialization of instances:

        Args:
            sdat (:class:`StagyyData`): the StagyyData instance owning the
                :class:`_Snaps` instance.
        Attributes:
            sdat (:class:`StagyyData`): the StagyyData instance owning the
                :class:`_Snaps` instance.