Given n points on a 2D plane, find if there is such a line parallel to y-axis that reflect the given set of points.

class Solution:
    def isReflected(self, points: List[List[int]]) -> bool:
        if not points:
            return True

        point_set = set()
        summation = max(points, key = lambda x: x[0])[0] + min(points, key = lambda x: x[0])[0]
        for (a, b) in points:
            point_set.add(str(a) + "c" + str(b))

        for (a, b) in points:
            mirror_point = str(summation - a) + "c" + str(b)
            if mirror_point not in point_set:
                return False
        return True