Python：“”未定义

这是我的代码：

# This program makes the robot calculate the average amount of light in a simulated room

from myro import *
init("simulator")

from random import*

def pressC():
    """ Wait for "c" to be entered from the keyboard in the Python shell """
    entry = " "
    while(entry != "c"):
        entry = raw_input("Press c to continue. ")
    print("Thank you. ")
    print

def randomPosition():
    """ This gets the robot to drive to a random position """
    result = randint(1, 2)
    if(result == 1):
        forward(random(), random())
    if(result == 2):
        backward(random(), random())

def scan():
    """ This allows the robot to rotate and print the numbers that each light sensors obtains """
    leftLightSeries = [0,0,0,0,0,0]
    centerLightSeries = [0,0,0,0,0,0]
    rightLightSeries = [0,0,0,0,0,0]
    for index in range(1,6):
        leftLight = getLight("left")
        leftLightSeries[index] = leftLightSeries[index] + leftLight
        centerLight = getLight("center")
        centerLightSeries[index] = centerLightSeries[index] + centerLight
        rightLight = getLight("right")
        rightLightSeries[index] = rightLightSeries[index] + rightLight
        turnRight(.5,2.739)
    return leftLightSeries
    return centerLightSeries
    return rightLightSeries

def printResults():
    """ This function prints the results of the dice roll simulation."""
    print " Average Light Levels "
    print "    L      C      R "
    print "========================="
    for index in range(1, 6):
        print str(index) + " " + str(leftLightSeries[index]) + " " + str(centerLightSeries[index]) + " " + str(rightLightSeries[index])

def main():
    senses()
    pressC()
    randomPosition()
    scan() 
    printResults()

main()

因此，当我运行我的程序时，我收到此错误。

NameError: global name 'leftLightSeries' is not defined

我知道我一定做错了与 return 语句相关的事情。我不确定是否只能在用户定义函数的末尾返回一个变量。如果这是真的，那么我可能应该分离 scan(): 函数。无论如何，我将不胜感激有关如何修复此错误的任何帮助。另外，这是我成功完成程序时正在寻找的结果：点击这里 https://i.stack.imgur.com/zgHOU.png

我希望完成如图所示的平均值，但此时我并不担心它们，只担心来自光传感器的值列表。我不需要达到这些确切的数字，模拟器中的数字会有所不同。

如果您想从以下位置退回多件商品scan()，不要使用三个单独的return声明。相反，请执行以下操作：

return leftLightSeries, centerLightSeries, rightLightSeries

此外，当您调用该函数时，您必须将变量分配给返回值；它不会自动创建具有相同名称的新局部变量。所以在main, call scan()像这样：

leftLightSeries, centerLightSeries, rightLightSeries = scan()