I’m trying to figure out where I went wrong with this exercise:

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

The idea is that they want a function that will take the length of a list, and then append that number to the end of the list.

So if the list is [23, 42, 108], the list is 3 items long and so the function would append ‘3’ and you would end up with [23, 42, 108, 3].

The listed solution is:

```
def append_size(lst):
lst.append(len(lst))
return lst
print(append_size([23, 42, 108]))
```

My attempted solution was:

```
def append_size(lst):
size = len(lst)
lst.append(size)
print(append_size([23, 42, 108]))
```

This returns a value of ‘None,’ and I’m not sure why. The function seems like it should be grabbing the length of the list (3) and saving it to the variable (size). Then - as I understand it - it should be appending ‘size’ (which is 3) to the end of the list. I highly suspect that the problem is that I’m not using ‘return,’ but I’m not sure. Thoughts?