Python 赋值前引用的局部变量“值”

我试图将这段代码转换成一个函数，但在赋值之前将局部变量“value”作为两个变量的错误引用。 为了更好地理解，我将粘贴整个代码

def allocator(item_mass,item_vol,truck_mass,truck_vol,truck_cost):
    n_items = len(item_vol)
    set_items = range(n_items)
    n_trucks = len(truck_cost)
    set_trucks = range(n_trucks)

    y = pulp.LpVariable.dicts('truckUsed', set_trucks,
    lowBound=0, upBound=1, cat=LpInteger)

    x = pulp.LpVariable.dicts('itemInTruck', (set_items, set_trucks), 
    lowBound=0, upBound=1, cat=LpInteger)

    prob = LpProblem("Truck allocatoin problem", LpMinimize)

    prob += lpSum([truck_cost[i] * y[i] for i in set_trucks])

    for j in set_items:
        prob += lpSum([x[j][i] for i in set_trucks]) == 1

    for i in set_trucks:
        prob += lpSum([item_mass[j] * x[j][i] for j in set_items]) <= truck_mass[i]*y[i]

        prob += lpSum([item_vol[j] * x[j][i] for j in set_items]) <= truck_vol[i]*y[i]

    for j in set_items:
        for i in set_trucks:
            x[j][i] <= y[i]


    prob.solve()

    x_soln = np.array([[x[i][j].varValue for i in set_items] for j in set_trucks])
    y_soln = np.array([y[i].varValue for i in set_trucks])

    lpstatus = LpStatus[prob.status]   #these two throw the error
    value_obj = value(prob.objective)  #


    return lpstatus,value_obj

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u在该行中使用的函数值

value_obj = value(prob.objective)

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未在任何地方定义。

此处没有任何内容会导致该错误。您已经删除了一些对问题至关重要的内容。它是在函数正在使用的纸浆库中定义的

value_obj = value(prob.objective)