example.py

class foo(Element)
     exists = sentaku.ContextualMethod()

    @exists.implemented_for(ViaDB)
    def exists(self):
        """
        Checks if the PXE server already exists
        """
        return self.db.exists("pxe_servers", name=self.name)

        return self.impl.db.session.query(
            self.impl.db["pxe_servers"]
        ).filter_by(
            name=self.name
        ).count() > 0

    @exists.implemented_for(ViaUI)
    def exists(self):
        """
        Checks if the PXE server already exists
        """
        # ** Here we are talking to the Sentaku system and asking for the implementation object,
        # ** or the endpoint object. This object is what enables us to "talk" to the endpoint, so
        # ** in this example it provides force_navigate, a browser, and other UI related things.
        # ** Over in the db module it will provide a db session.

        # ** Notice also how the rest of the UI stuff, like pxe_tree remains unchanged. This is our
        # ** desire, to leave as much of the objects code intact as possible.
        return self.can_navigate_to(pxe_tree, self.name)

        self.impl.force_navigate('infrastructure_pxe_servers')
        try:
            pxe_tree(self.name)
            return True
        except CandidateNotFound:
            return False
        except NoSuchElementException:
            return False