I wanted to append the last two items of “lst” on to the end of lst. My code does this but puts the last to items in a sub-list. Why is it doing this?

```
#Write your function here
def append_sum(lst):
lst.append(lst[-2:])
return lst
#Uncomment the line below when your function is done
print(append_sum([1, 1, 2]))
```

This outputs

```
[1, 1, 2, [1, 2]]
```