Python Code Challenges: Lists first

1.Append Sum

https://www.codecademy.com/courses/learn-python-3/articles/python-code-challenges-lists

Task is simple:

Take list, add two last element together and then append to the same exact list three times.

I wrote this piece of code

```
def append_sum(lst):
for x in range(3):
lst.append(lst[-1] + lst[-2])
print(lst)
append_sum([1, 1, 2])
```

#[1, 1, 2, 3, 5, 8]

According to the task this is correct answer. But after checking it system says it is incorrect.

I`ve load this snippet in VSCode and its gave me the same result.

Help button gave me this:

```
def append_sum(lst):
lst.append(lst[-1] + lst[-2])
lst.append(lst[-1] + lst[-2])
lst.append(lst[-1] + lst[-2])
return lst
print(append_sum([1, 1, 2]))
```

Which is output the same result. Well, my solution is better but it is incorrect for some reason. I am a bit confused by that.