Method swap12

chapter05/src/main/java/com/seaofnodes/simple/node/Node.java:345–350

()

    // Swap inputs without letting either input go dead during the swap.
    Node swap12() {
        Node tmp = in(1);
        _inputs.set(1,in(2));
        _inputs.set(2,tmp);
        return this;
    }

    // does this node contain all constants?
    // Ignores in(0), as is usually control.