[jgalt212]

why not inside of __init__

  self.accessed_keys = set()

instead of

    @property
    def accessed_keys(self):
        return self._accessed_keys

[Jaxan]

With the @property you only get the “getter” and not the “setter”.

[eurleif]

But that doesn't accomplish much, because you can still do: `d.accessed_keys.add('foo')`.

[Jaxan]

That’s right