def __init__(self,
                 window,
                 items,
                 sids,
                 cap_multiple=2,
                 dtype=np.float64,
                 initial_dates=None):

        self._pos = window
        self._window = window

        self.items = _ensure_index(items)
        self.minor_axis = _ensure_index(sids)

        self.cap_multiple = cap_multiple

        self.dtype = dtype
        if initial_dates is None:
            self.date_buf = np.empty(self.cap, dtype='M8[ns]') * pd.NaT
        elif len(initial_dates) != window:
            raise ValueError('initial_dates must be of length window')
        else:
            self.date_buf = np.hstack(
                (
                    initial_dates,
                    np.empty(
                        window * (cap_multiple / 1),
                        dtype='datetime64[ns]',
                    ),
                ),
            )

        self.buffer = self._create_buffer()
dataset/ETHPy150Open quantopian/zipline/zipline/utils/data.py/RollingPanel.__init__/operator `-` -> `/`