I don't know if it's kosher, but I saw no reason not to use the built-in sort method for lists!

```
m = len(nums1)
n = len(nums2)
combo = nums1 + nums2
combo.sort()
x = m + n
if (x % 2): # odd number of merged array elements -- median equals middle element
mid = (x - 1) / 2
median = combo[mid]
else: # even number of merged array elements -- median equals average of middle two elements
mid = x / 2
median = (combo[mid-1] + combo[mid]) / float(2)
```