def rolling_mean_score(scoring, days=2):
    """Compute rolling mean fantasy score over given number of days
    
    Args:
        scoring (pd.DataFrame) : DataFrame consisting of player_id and
                                fantasy_total_points
        
        days (int) : rolling period to be used
    
    Returns:
        rolling mean score over given days
    """
    scores = scoring.groupby("player_id")["standardized_fantasy_total_points"].rolling(days, min_periods=days).mean()
    scores = scores.reset_index().set_index("level_1").drop(columns="player_id")
    return scores