def _stats(self, lambda_, N):
        z = exp(-lambda_)
        zN = exp(-lambda_*N)
        mu = z/(1.0-z)-N*zN/(1-zN)
        var = z/(1.0-z)**2 - N*N*zN/(1-zN)**2
        trm = (1-zN)/(1-z)
        trm2 = (z*trm**2 - N*N*zN)
        g1 = z*(1+z)*trm**3 - N**3*zN*(1+zN)
        g1 = g1 / trm2**(1.5)
        g2 = N**4 * zN*(1+4*zN+zN*zN) - z*(1+4*z+z*z)*trm**4
        g2 = g2 / trm2 / trm2
        return mu, var, g1, g2
dataset/ETHPy150Open scipy/scipy/scipy/stats/_discrete_distns.py/boltzmann_gen._stats/swapped operands of `-`