373. Find K Pairs with Smallest Sums

class Solution(object):
    def kSmallestPairs(self, nums1, nums2, k):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :type k: int
        :rtype: List[List[int]]
        """
        res=[]
        pq=[]
        def push(i,j):
            if i