def add(self, revision, operators):
        """
        Add a revision to the index.

        :param revision: The revision.
        :type  revision: :class:`Revision` or :class:`LazyRevision`
        """
        ir = IndexedRevision(
            revision=revision, operators=[operator.name for operator in operators]
        )
        self._revisions[revision.key] = ir
        return ir
Add a revision to the index.

        :param revision: The revision.
        :type  revision: :class:`Revision` or :class:`LazyRevision`