human
Solve the following python programming problem given the following code:
def removeCallback(self, service, nodeIdentifier, callback) : 
    def interaction(cursor) : 
        cursor.execute ('DELETE FROM callbacks
                              WHERE service=%s and node=%s and uri=%s', (service.full (), nodeIdentifier, callback)) 
        if (cursor.rowcount != 1) : 
            raise error.NotSubscribed () 
last = (not self._countCallbacks (cursor, service, nodeIdentifier)) 
        return last 
return self.dbpool.runInteraction (service) 

    
    

    Fix the buggy line: return self.dbpool.runInteraction (service)
assistant
#Here is Python program to fix the buggy line: return self.

return self.dbpool.runInteraction (def interaction()