Get a Panel that is the current data in view. It is not safe to persist
        these objects because internal data might change

def get_current(self):
        """
        Get a Panel that is the current data in view. It is not safe to persist
        these objects because internal data might change
        """

        where = slice(self._oldest_frame_idx(), self._pos)
        major_axis = pd.DatetimeIndex(deepcopy(self.date_buf[where]), tz='utc')
        return pd.Panel(self.buffer.values[:, where, :], self.items,
                        major_axis, self.minor_axis, dtype=self.dtype)