recursion python

class Solution(object):
    def intersect(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        map = {}
        if len(nums2) > len(nums1):
            return Solution.intersect(self, nums2, nums1)
        for num in nums1:
            map[num] = map.get(num, 0) + 1
        i = 0
        for num in nums2:
            if map.get(num) > 0:
                nums1[i] = num
                map[num]= map.get(num) - 1
                i += 1
        return nums1[0 : i]