增加默认值，增加缺省值

默认值：
def print_lol(the_list,level=0):
    for each_item in the_list:
        if isinstance(each_item,list):
            print_lol(each_item,level+1)
        else:
            for tab_stop in range(level):
                    print ("\t" *level,end='')
            print(each_item)

names = ['John','Eric',['Cleese','Idle'],'Michael',['Palin']]

print_lol(names,1)

缺省值：

def print_lol(the_list,indent=False,level=0):
    for each_item in the_list:
        if isinstance(each_item,list):
            print_lol(each_item,indent,level+1)
        else:
            if indent:
                for tab_stop in range(level):
                    print ("\t" *level,end='')
            print(each_item)

names = ['John','Eric',['Cleese','Idle'],'Michael',['Palin']]

print_lol(names,True,1)