human
Solve the following python programming problem given the following code:
def __init__(self, zk, zk_path, on_join = None, on_leave = None, member_filter = None, member_factory = None) : 
    'Initialize the ServerSet, ensuring the zk_path exists.

    Args:
      zk - An instance of a Kazoo client.
      zk_path - The path to watch for children in.  If the path does not exist,
                it will be watched for creation.
      on_join - An optional function to call when members join the node.
      on_leave - An optional function to call when members leave the node.
      member_filter - An optional function to filter children from ZK.
      member_factory - An optional function to create a Member object from a znode.
    ' 
    def noop(* args, **kwargs) : 
        pass 
def true(* args, **kwargs) : 
        return True 
self._log = ROOT_LOG.getChild (('[%s]' % zk_path)) 
    self._log.info (('TellApart ServerSet intializing on path %s' % zk_path)) 
    if (not isinstance (zk, KazooClient)) : 
        raise TypeError ('zk must be an instance of a KazooClient') 
if (not zk.connected) : 
        raise Exception ('zk must be in a connected state.') 
self._zk_path = zk_path 
    self._zk = zk 
    self._nodes = set () 
    self._members = { 
        
} 
    self._on_join = (on_join or noop) 
    self._on_leave = (on_leave or noop) 
    self._notification_queue = Queue (0) 
    self._watching = False 
    self._cb_blocker = self._CallbackBlocker () 
    self._member_filter = (member_filter or true) 
    self._member_factory = (member_factory or Member.from_node) 
    self._running = True 
    self._worker = gevent.spawn (self._notification_worker) 
    if (on_join or zk_path) : 
        self._monitor () 

    
    

    Fix the buggy line: if (on_join or zk_path) :
assistant
#Here is Python program to fix the buggy line: if (on_join or zk_path) :
.

if (on_join or on_leave) :