问尝试选择用户定义的类时出错

EN

class wma :

    def __init__(self) : pass

    def isConsistent(self, df, nConsecutive) :
        sum = 0
        for i in np.arange(1, nConsecutive + 1) :
            sum += i

        weights = []
        for val in np.arange(1, nConsecutive + 1) :
            weight = val / sum
            weights.append(weight)
        
        maxWMA = 0
        for weight in weights :
            maxWMA += weight

        result = df[0].rolling(nConsecutive).apply(lambda x : np.sum(weights * x))
        currentWMA = results.iloc[-1]

        if currentWMA == maxWMA :
            return True
        else :
            return False

wma = wma()
file = open("wma", "wb")
pickle.dump(wma, file)
file.close()

PicklingError: Can't pickle <class '__main__.wma'>: it's not the same object as __main__.wma