Hello, I’m wondering why this line of code runs

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

but my one does not:

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

I realise the first is far less clunky, but do not see why mine does not run. Could someone please explain why my use of return is wrong, am I not understanding the purpose of it?