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 'builtin_function_or_method' has no len()

I don't understand why this fails or why it doesn't like len().

```
def median(series):
s = series.sort
m = len(s) / 2
if len(s) % 2 == 0:
x = (float(s[m]) + float(s[m-1])) / 2.0
else:
x = s[int(m)]
return x
```