code: protected void initializeGraph() {
          mGraph = new Graph(getContext());
          addView(mGraph);
  
          mGraphOverlay = new GraphOverlay(getContext());
          addView(mGraphOverlay);
  
          mLegend = new Legend(getContext());
          addView(mLegend);
      }
docs: This is the main entry point after the graph has been inflated. Used to initialize the graph
  and its corresponding members.