public void allocateOperand() throws UnknownInstructionException {
		if (depth == MAX_PARSE_DEPTH) {
			throw new UnknownInstructionException("Exceeded maximum parse depth");
		}
		ConstructState opstate = new ConstructState(point);
		breadcrumb[depth++] += 1;
		point = opstate;
		breadcrumb[depth] = 0;
	}
Move down to a particular child of the current node.  Store what would be the next sibling to walk
@param i is the index of the desired child
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/processors/sleigh/ParserWalker.java