def censorrevision(tr, node, tombstone=b''):
    """Remove the content of a single revision.

        The specified ``node`` will have its content purged from storage.
        Future attempts to access the revision data for this node will
        result in failure.

        A ``tombstone`` message can optionally be stored. This message may be
        displayed to users when they attempt to access the missing revision
        data.

        Storage backends may have stored deltas against the previous content
        in this revision. As part of censoring a revision, these storage
        backends are expected to rewrite any internally stored deltas such
        that they no longer reference the deleted content.
        """
