Second derivative of the C-Log-Log ink function

        Parameters
        ----------
        p : array-like
            Mean parameters

        Returns
        -------
        g''(p) : array
            The second derivative of the CLogLog link function

def deriv2(self, p):
        """
        Second derivative of the C-Log-Log ink function

        Parameters
        ----------
        p : array-like
            Mean parameters

        Returns
        -------
        g''(p) : array
            The second derivative of the CLogLog link function
        """
        p = self._clean(p)
        fl = np.log(1 - p)
        d2 = -1 / ((1 - p)**2 * fl)
        d2 *= 1 + 1 / fl
        return d2