human
Solve the following python programming problem given the following code:
def before_send(self) : 
    def on_session_start(event) : 
        try : 
            self.xmpp.send_presence () 
            self.xmpp.get_roster () 
            self._session_started = True 
except self.lib.exceptions.XMPPError as e : 
            raise MessengerWarmupException (('XMPP Error: %s' % e)) 
self.xmpp = self.lib.ClientXMPP (self.from_jid, self.password) 
    self.xmpp.add_event_handler ('session_start', self) 
    result = self.xmpp.connect (address = (self.host, self.port), reattempt = False, use_tls = self.use_tls, use_ssl = self.use_ssl) 
    if result : 
        self.xmpp.process (block = False) 

    
    

    Fix the buggy line: self.xmpp.add_event_handler ('session_start', self)
assistant
#Here is Python program to fix the buggy line: self.

self.xmpp.add_event_handler ('session_start', def on_session_start()