@staticmethod
    def _combine(Ms, sums, ns):
        mu = np.nansum(sums, axis=0) / ns.sum(axis=0)
        return np.nansum(Ms + ns*(mu - sums/ns)**2, axis=0)
dataset/ETHPy150Open bokeh/datashader/datashader/reductions.py/m2._combine/swapped operands of `-`