这段代码会出现TypeError: There are no type variables left in dict[{'id': '1001', 'name': '张三', 'english': 100, 'python': 100, 'java': 100}]这个问题,是为什么呢?
```
mode=input('请选择排序方式(1.按英语成绩排序 2.按python成绩排序 3.按java成绩排序 0.按总成绩排序)')
if mode=='1':
student_new.sort(key=lambda a:int(a['english']),reverse=asc_or_desc_bool)
elif mode=='2':
student_new.sort(key=lambda x:int(x['python']),reverse=asc_or_desc_bool)
elif mode=='3':
student_new.sort(key=lambda x:int(x['java']),reverse=asc_or_desc_bool)
elif mode=='0':
student_new.sort(key=lambda x:int(x['english'])+int(x['python'])+int(x['java']),reverse=asc_or_desc_bool)
else:
```