'Wait on the barrier to be cleared
:returns: True if the barrier has been cleared, otherwise
False.
:rtype: bool'

def wait(self, timeout=None):

    cleared = self.client.handler.event_object()
    def wait_for_clear(event):
        if (event.type == EventType.DELETED):
            cleared.set()
    exists = self.client.exists(self.path, watch=wait_for_clear)
    if (not exists):
        return True
    cleared.wait(timeout)
    return cleared.is_set()
