def get_key(self, fileobj):
        """Return the key associated to a registered file object.

        Returns:
        SelectorKey for this file object
        """
        mapping = self.get_map()
        if mapping is None:
            raise RuntimeError('Selector is closed')
        try:
            return mapping[fileobj]
        except KeyError:
            raise KeyError("{0!r} is not registered".format(fileobj))
Return the key associated to a registered file object.

        Returns:
        SelectorKey for this file object
        
kafka/vendor/selectors34.py