Method push

src/main/java/field/graphics/FLine.java:2167–2173

()

		return this;
	}

	public FLine pop() {

		if (stateStack.size() == 0)
			throw new IllegalArgumentException("pop() too many times");
		State s = stateStack.remove(stateStack.size() - 1);
		heading = heading.duplicate();
		return moveTo(nodes.get(s.index).to);
	}