handAssignNode(node);
assigned.add(node);
    public void visitNode(FlatNode node)     {	if (node.contents instanceof SIRFilter) {	    handAssignNode(node);	    return;	}	if (node.contents instanceof SIRJoiner) {	    if (!(node.edges[0].contents instanceof SIRJoiner)) {		joiners.add(node);		handAssignNode(node);		return;	    }	}    }