@staticmethod
def tree_remains_unsure_and_best_upstream_router_reelected(interface:
    'TreeInterfaceDownstream'):
    """
        Tree remains in Unsure state AND
        BestUpstream neighbor changes

        OR

        Tree remains in Unsure state AND
        BestUpstream neighbor transmitted IamUpstream message that doesnt cause a change of the BestUpstream neighbor
        """
    interface.logger.debug(
        'tree_remains_unsure_and_best_upstream_router_reelected')
    interface.send_no_interest()
