Method unkill

chapter23/src/main/java/com/seaofnodes/simple/node/Node.java:293–296

()

    // Test "keep" status
    public boolean iskeep() { return _outputs.find(null) != -1; }
    public void unkill() {
        if( unkeep().isUnused() )
            kill();
    }
    public void isKill() {
        if( isUnused() )
            kill();