human
Solve the following python programming problem given the following code:
def _do_fetch(self, conn) : 
    'Takes a database connection and waits for requests for events from
        the _event_fetch_list queue.
        ' 
    event_list = [] 
    i = 0 
    while True : 
        try : 
            with self._event_fetch_lock : 
                event_list = self._event_fetch_list 
                self._event_fetch_list = [] 
                if (not event_list) : 
                    single_threaded = self.database_engine.single_threaded 
                    if (single_threaded or (i > EVENT_QUEUE_ITERATIONS)) : 
                        self._event_fetch_ongoing -= 1 
                        return 
else : 
                        self._event_fetch_lock.wait (EVENT_QUEUE_TIMEOUT_S) 
                        i += 1 
                        continue 
i = 0 
event_id_lists = zip (* event_list) [0] 
            event_ids = [item for sublist in event_id_lists for item in sublist] 
            rows = self._new_transaction (conn, 'do_fetch', [], None, self._fetch_event_rows, event_ids) 
            row_dict = { r ['event_id'] : r for r in e } 
            def fire(lst, res) : 
                for (ids, d) in lst : 
                    if (not d.called) : 
                        try : 
                            with PreserveLoggingContext () : 
                                d.callback ([res [i] for i in ids if (i in res)]) 
except : 
                            logger.exception ('Failed to callback') 
with PreserveLoggingContext () : 
                reactor.callFromThread (fire, event_list, row_dict) 
except Exception as e : 
            logger.exception ('do_fetch') 
            def fire(evs) : 
                for (_, d) in evs : 
                    if (not d.called) : 
                        with PreserveLoggingContext () : 
                            d.errback (e) 
if event_list : 
                with PreserveLoggingContext () : 
                    reactor.callFromThread (fire, event_list) 

    
    

    Fix the buggy line: row_dict = { r ['event_id'] : r for r in e }
assistant
#Here is Python code to fix the buggy line: row_dict = { r ['event_id'] : r for r in e }
.

row_dict = { r ['event_id'] : r for r in rows }