def _key_from_fd(self, fd):
        """Return the key associated to a given file descriptor.

        Parameters:
        fd -- file descriptor

        Returns:
        corresponding key, or None if not found
        """
        try:
            return self._fd_to_key[fd]
        except __HOLE__:
            return None
dataset/ETHPy150Open dpkp/kafka-python/kafka/selectors34.py/_BaseSelectorImpl._key_from_fd