Error de Sintaxis: Sintaxis inválida

class Libro:
    def __init__(self, autor, title):
        self.autor = autor
        self.title = title

    def __inter__(BookCase)

    def __str__(self):
        return f'{self.author}, {self.title}'
        personal = Libro(John Green, Paper Towns)

    def __eq__(self, otro):
        if self.autor == otro.autor y self.title == otro.title:

from libro import Libro


class BookCase:
    def __iter__(self):
        pass
    def __inter__(self):
       self.libros = 

    def add_books(self, libro):
        self.libros.append(libro)