It's simple to use the set function and return the overlap of the two list.

```
def intersection(self, nums1, nums2):
"""
:type nums1: List[int]
:type nums2: List[int]
:rtype: List[int]
"""
if nums1==[] or nums2==[]:return []
set1=set(nums1)
set2=set(nums2)
return list(set1&set2)
```