nameerror - Python: ' ' is not defined -

here code:

# program makes robot calculate average amount of light in simulated room  myro import * init("simulator")  random import*  def pressc():     """ wait "c" entered keyboard in python shell """     entry = " "     while(entry != "c"):         entry = raw_input("press c continue. ")     print("thank you. ")     print  def randomposition():     """ gets robot drive random position """     result = randint(1, 2)     if(result == 1):         forward(random(), random())     if(result == 2):         backward(random(), random())  def scan():     """ allows robot rotate , print numbers 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]     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():     """ function prints results of dice roll simulation."""     print " average light levels "     print "    l      c      r "     print "========================="     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() 

so, getting error when run program.

nameerror: global name 'leftlightseries' not defined 

i understand must doing wrong related return statement. i'm not sure if can return 1 variable @ end of user-defined function. if true, should separate scan(): function. anyways, appreciate on how fix error. also, result looking when complete program: click here

i looking complete average values picture shows, not worried them @ point, list of values light sensors. not need reach exact numbers, numbers vary in simulator.

if want return multiple items scan(), don't use 3 separate return statements. instead, this:

return leftlightseries, centerlightseries, rightlightseries 

also, when call function, have assign variable(s) returned values; won't automatically create new local variables same names. in main, call scan() this:

leftlightseries, centerlightseries, rightlightseries = scan()