human
Solve the following python programming problem given the following code:
def _loop_darwin(self) : 
    'loop implementation for darwin platform' 
    from fsevents import Observer 
    from fsevents import Stream 
    from fsevents import IN_MODIFY 
    observer = Observer () 
    handler = self._handle 
    def fsevent_callback(event) : 
        if (event.mask == IN_MODIFY) : 
            handler (event) 
for watch_this in stream.watch_dirs : 
        stream = Stream (fsevent_callback, watch_this, file_events = True) 
        observer.schedule (stream) 
observer.daemon = True 
    observer.start () 
    try : 
        import time 
        while True : 
            time.sleep (99999) 
except (SystemExit, KeyboardInterrupt) : 
        pass 

    
    

    Fix the buggy line: for watch_this in stream.watch_dirs :
assistant
#Here is Python program to fix the buggy line: for watch_this in stream.

for watch_this in self.watch_dirs :