Python: Custom implementation

class DisjointSet():

    class Node():
        def __init__(self, value: int):
            self.value = value
            self.parent = self
            self.size = 1
 
    def __init__(self):
        self.seen_values = set()

    def make_set(self, value):
        if value not in self.seen_values:
            node = Node(value)
        self.sets.append(node)

    # optimized find which does path splitting to update parents during find
    def find(self, node):
        while node.parent != node:
            node, node.parent = node.parent. node.parent.parent
        return node

    def union(self, node1, node2):
        node1_rep = self.find(node1)
        node2_rep = self.find(node2)

        if node1_rep == node2_rep:
            return # both are in the same set

        # we want the node1_rep's size to be >= node2_rep
        if node1_rep.size < node2_rep.size:
            node1_rep, node2_rep = node2_rep, node1_rep

        node2_rep.parent = node1_rep
        node1_rep.size += node2_rep.size