human
Solve the following python programming problem given the following code:
@ defer.inlineCallbacks 
def add_account_data_to_room(self, user_id, room_id, account_data_type, content) : 
    'Add some account_data to a room for a user.
        Args:
            user_id(str): The user to add a tag for.
            room_id(str): The room to add a tag for.
            account_data_type(str): The type of account_data to add.
            content(dict): A json object to associate with the tag.
        Returns:
            A deferred that completes once the account_data has been added.
        ' 
    content_json = json.dumps (content_json) 
    def add_account_data_txn(txn, next_id) : 
        self._simple_upsert_txn (txn, table = 'room_account_data', keyvalues = { 
            'user_id' : user_id, 
            'room_id' : room_id, 
            'account_data_type' : account_data_type, 
}, values = { 
            'stream_id' : next_id, 
            'content' : content_json, 
}) 
        txn.call_after (self._account_data_stream_cache.entity_has_changed, user_id, next_id) 
        self._update_max_stream_id (txn, next_id) 
with self._account_data_id_gen.get_next () as next_id : 
        (yield self.runInteraction ('add_room_account_data', add_account_data_txn, next_id)) 
result = self._account_data_id_gen.get_max_token () 
    defer.returnValue (result) 

    
    

    Fix the buggy line: content_json = json.dumps (content_json)
assistant
#Here is Python program to fix the buggy line: content_json = json.

content_json = json.dumps (content)