In Practice Makes Perfect: 15. Median, I came up with this code.

Python tells me: "median([4, 5, 5, 4]) returned 5.0 instead of 4.5". Which I don't understand since I've already sorted the list. Where did I go wrong?

```
def median(numbers):
snumbers = sorted(numbers)
if len(snumbers) % 2 == 0:
index1 = len(snumbers) / 2
index2 = index1 + 1
average = (snumbers[index1] + snumbers[index2]) / 2.0
return average
else:
index3 = len(snumbers)/2
average = snumbers[index3]
return average
```

Thank you!