human
Solve the following python programming problem given the following code:
def get_requests(self) : 
    requests = [None] 
    def on_select_return(success, db_results) : 
        assert success 
        requests [0] = db_results.fetchall () 
db.execute_cb (db.push_requests.select (), <MASK>) 
    return requests [0] 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
def on_select_return(