@Override
	public Address getPCAddress() {
		if (bInput) {
			return Address.NO_ADDRESS;
		}
		if (def != null) {
			return def.getSeqnum().getTarget();
		}
		if (descend.size() == 1) {
			return descend.get(0).getSeqnum().getTarget();
		}
		return Address.NO_ADDRESS;
	}
This type of Varnode is a node in an Abstract Syntax Tree
It keeps track of its defining PcodeOp (in-edge) and PcodeOps which use it (out-edges)
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/VarnodeAST.java