Merge the
Context into the graph. Assumes that the specified
node is not in the graph but that all endpoints in the
successors and
predecessors (with the exception of
loops) are. If the cluster is not present in the graph, then it will
be added with no attributes with a parent of the root graph.
Note that
& and
decompose are
not
quite inverses, as this function will add in the cluster if it does
not yet exist in the graph, but
decompose will not delete it.