def get(key, *, expunge=False):
    """Return the contents cached under the given key.

        :param key: The key identifying the contents you want to retrieve.
        :type key: str
        :param expunge: A flag indicating whether the file contents should
            also be removed from the cache.
        :type expunge: bool
        :return: The contents of the cached file or None if the given id isn't
            in the cache (or it's already expired).
        :rtype: bytes or str, depending on the original contents.
        """
