code: private void updateCursorsInScene(GVRScene scene, boolean add) {
          synchronized (mCursors) {
              for (Cursor cursor : mCursors) {
                  if (cursor.isActive()) {
                      if (add) {
                          addCursorToScene(cursor);
                      } else {
                          removeCursorFromScene(cursor);
                      }
                  }
              }
          }
      }
docs: Add or remove the active cursors from the provided scene.
  
  @param scene The GVRScene.
  @param add   <code>true</code> for add, <code>false</code> to remove