Link.
inverse
Inverse of the link function. Just a placeholder.
z : array-like
z is usually the linear predictor of the transformed variable in the IRLS algorithm for GLM.
The value of the inverse of the link function g^(-1)(z) = p :
statsmodels.genmod.families.links.Link.deriv2
statsmodels.genmod.families.links.Link.inverse_deriv