def main():    #To judge whether a list is empty. We can use "if list0" instead of "if len(list0)". But we must be aware that [] is not None and [] is not False.    list1 = [10, 12, 23, 24]    list2 = []    if list1:        print "list1: {}".format(list1)    else:        print "list1 is an empty list: {}".format(list1)    if list2:        print "list2: {}".format(list2)    else:        print "list2 is an empty list: {}".format(list2)    #[] is not None. [] is not False.    print list2==None     #False    print list2==False    #False    print list2 is None   #False    print list2 is False  #False    #Get the index while traverse a list.    for index, value in enumerate(list1):        print "index: {}, value: {}".format(index, value)if __name__ == ‘__main__‘:    main()else:    print "Being imported as a module."

lxw Practice$ python collectionTips.py list1: [10, 12, 23, 24]list2 is an empty list: []FalseFalseFalseFalseindex: 0, value: 10index: 1, value: 12index: 2, value: 23index: 3, value: 24lxw Practice$