Usage – ​using these models:

>>> a4
    <Article: Oxygen-free diet works wonders>
>>> p2
    <Publication: Science News>
>>> p2.article_set.all()
    [
        <Article: NASA finds intelligent life on Earth>,
        <Article: NASA uses Python>,
        <Article: Oxygen-free diet works wonders>,
    ]
>>> a4.publications.toggle(p2) # the relation is removed
>>> p2.article_set.all()
    [
        <Article: NASA finds intelligent life on Earth>,
        <Article: NASA uses Python>,
    ]
>>> a4.publications.toggle(p2) # the relation is added
>>> p2.article_set.all()
    [
        <Article: NASA finds intelligent life on Earth>,
        <Article: NASA uses Python>,
        <Article: Oxygen-free diet works wonders>,
    ]
>>> p2.article_set.toggle(a4) # and… removed again (can be toggled from either model)
    [
        <Article: NASA finds intelligent life on Earth>,
        <Article: NASA uses Python>,
    ]