How to Fix Memento Errors

class Editor:
    def __init__(self):
        self.content=''; self.cursor=0; self.selection=''
    def save(self):
        return (self.content,self.cursor,self.selection)  # exposes internals
    def restore(self,s):
        self.content,self.cursor,self.selection=s  # tuple coupling

from dataclasses import dataclass
class Editor:
    def __init__(self):
        self.content=''; self.cursor=0; self.selection=''
    def save(self): return Memento(self.content,self.cursor,self.selection)
    def restore(self,m):
        self.content,m.cursor,m.selection = m.content,m.cursor,m.selection
@dataclass
class Memento:
    content: str; cursor: int; selection: str
class History:
    def __init__(self): self.states=[]
    def push(self,m): self.states.append(m)
    def pop(self): return self.states.pop()
ed=Editor(); history=History()
history.push(ed.save())
ed.content='new'
ed.restore(history.pop())