tileAssignment.put(coord, node); SIRassignment.put(node.contents, coord);
layout.tileAssignment.put(coord, node); layout.SIRassignment.put(node.contents, coord);
    private static void assign(Coordinate coord, FlatNode node)     {	if (node == null) {	    tileAssignment.remove(coord);	    return;	}	tileAssignment.put(coord, node);	SIRassignment.put(node.contents, coord);    }