private static int computeRedLevel(int sz) {
		int level = 0;
		for (int m = sz - 1; m >= 0; m = m / 2 - 1)
			level++;
		return level;
	}
Find the level down to which to assign all nodes BLACK.  This is the
last `full' level of the complete binary tree produced by
buildTree. The remaining nodes are colored RED. (This makes a `nice'
set of color assignments wrt future insertions.) This level number is
computed by finding the number of splits needed to reach the zeroeth
node.  (The answer is ~lg(N), but in any case must be computed by same
quick O(lg(N)) loop.)
Ghidra/Framework/Generic/src/main/java/ghidra/util/datastruct/RedBlackKeySet.java