https://www.codecademy.com/courses/python-intermediate-en-rCQKw/2/5?curriculum_id=4f89dab3d788890003000096#

Oops, try again. median([1]) resulted in an error: object of type 'NoneType' has no len()

i expected it to return the median

```
def median(lists):
lists = lists.sort()
if lists == 1:
return 1
elif len(lists) % 2 == 0:
median1 = len(lists) // 2
median2 = median1 + 1
median3 = (lists[median1] + lists[median2]) / 2.0
return median3
elif len(lists) % 2 == 1:
median = len(lists) / 2
median = lists[median]
return median
```