'The log-likelihood function in terms of the fitted mean response.
Parameters
endog : array-like
Endogenous response variable
mu : array-like
The fitted mean response values
iweights : array-like
1d array of weights. The default is 1.
scale : float
The scale parameter. The default is 1.
Returns
llf : float
The value of the loglikelihood function evaluated at
(endog,mu,iweights,scale) as defined below.
Notes
This is not implemented because of the complexity of calculating an
infinite series of sums.'

def loglike(self, endog, mu, iweights=1.0, scale=1.0):

    return np.nan
