'Derivative of C-Log-Log transform link function
Parameters
p : array-like
Mean parameters
Returns
g\'(p) : array
The derivative of the CLogLog transform link function
Notes
g\'(p) = - 1 / ((p-1)*log(1-p))'

def deriv(self, p):

    p = self._clean(p)
    return (1.0 / ((p - 1) * np.log((1 - p))))
