def METHOD_NAME(
    self, params: Union[DictBox, Dict[str, np.array]], T: Union[float, np.array], Xs: DataframeSlicer
) -> Union[np.array, ArrayBox]:
    lambda_params = params["lambda_"]
    log_lambda_ = Xs["lambda_"] @ lambda_params
    rho_params = params["rho_"]
    log_rho_ = Xs["rho_"] @ rho_params
    return log_rho_ - log_lambda_ + np.expm1(log_rho_) * (np.log(T) - log_lambda_)