:param model: GPflow model with objective tensor.
        :param session: Session where optimization will be run.
        :param var_list: List of extra variables which should be trained during optimization.
        :param feed_dict: Feed dictionary of tensors passed to session run method.
        :param maxiter: Number of run interation.
        :param initialize: If `True` model parameters will be re-initialized even if they were
            initialized before in the specified session.
        :param anchor: If `True` trained variable values computed during optimization at
            particular session will be synchronized with internal parameter values.
        :param step_callback: A callback function to execute at each optimization step.
            Callback takes an arbitrary list of arguments. Input arguments depend on
            interface implementation.
        :param kwargs: This is a dictionary of extra parameters for session run method.

def minimize(self, model, session=None, var_list=None, feed_dict=None,
                 maxiter=1000, initialize=True, anchor=True, step_callback=None, **kwargs):
        """
        :param model: GPflow model with objective tensor.
        :param session: Session where optimization will be run.
        :param var_list: List of extra variables which should be trained during optimization.
        :param feed_dict: Feed dictionary of tensors passed to session run method.
        :param maxiter: Number of run interation.
        :param initialize: If `True` model parameters will be re-initialized even if they were
            initialized before in the specified session.
        :param anchor: If `True` trained variable values computed during optimization at
            particular session will be synchronized with internal parameter values.
        :param step_callback: A callback function to execute at each optimization step.
            Callback takes an arbitrary list of arguments. Input arguments depend on
            interface implementation.
        :param kwargs: This is a dictionary of extra parameters for session run method.

        """
        raise NotImplementedError()