void addEdgeColor() {
		if (sources.size() == 1) {
			CtrlNGram zeroGram = ngrams.get(0);
			CtrlVertex src = sources.get(0);
			int edgeColor;
			for (edgeColor = 0; edgeColor < src.sinks.size(); ++edgeColor) {
				if (src.sinks.get(edgeColor) == this) {
					break;
				}
			}
			zeroGram.hash = Pinning.hashTwo(zeroGram.hash, edgeColor);
		}
	}
Add some additional color to the 0-gram hash for this node.
If the node has exactly 1 incoming edge, hash in the index of that edge,
i.e. the position of that edge within the last of sink edges of the parent vertex.
This distinguishes the node as either the true or false action after a conditional branch, or
by associating the node with a particular case of a switch branch.
Ghidra/Features/CodeCompare/src/main/java/ghidra/features/codecompare/graphanalysis/CtrlVertex.java