def _check_cutoff(self):
        """
        Returns a function to stop the search of the investigated node of the
        ArciDispatch algorithm.

        :return:
            A function to stop the search.
        :rtype: (int | float) -> bool
        """

        if self.cutoff is not None:

            cutoff = self.cutoff  # Namespace shortcut for speed.

            def check_cutoff(distance):
                """
                Stops the search of the investigated node of the ArciDispatch
                algorithm.

                :param distance:
                    Distance from the starting node.
                :type distance: float, int

                :return:
                    True if distance > cutoff, otherwise False.
                :rtype: bool
                """

                return distance > cutoff  # Check cutoff distance.

        else:  # cutoff is None.
            # noinspection PyUnusedLocal
            def check_cutoff(distance):
                return False

        return check_cutoff
Returns a function to stop the search of the investigated node of the
        ArciDispatch algorithm.

        :return:
            A function to stop the search.
        :rtype: (int | float) -> bool