private int getMaxLevel(Map<CodeBlockVertex, Integer> levelMap) {
		int maxLevel = -1;
		for (Integer level : levelMap.values()) {
			if (level > maxLevel) {
				maxLevel = level;
			}
		}
		return maxLevel;
	}
This command will organize a program tree into levels from the bottom up.  In other words, all
the leaf functions are at the same level and all the functions that only call leaf functions are
one level less and so on and so forth.
Ghidra/Features/Base/src/main/java/ghidra/app/cmd/module/ComplexityDepthModularizationCmd.java