@Override
	public VisualGraphLayout<FcgVertex, FcgEdge> getLayout() {
		return layout;
	}
Returns the largest level (the furthest level from the source node) in the given 
direction 

@param direction the direction to search
@return the largest level
Ghidra/Features/GraphFunctionCalls/src/main/java/functioncalls/graph/FunctionCallGraph.java