code: @TargetApi(18)
      public void startRangingBeaconsInRegion(@NonNull Region region) throws RemoteException {
          if (!isBleAvailableOrSimulated()) {
              LogManager.w(TAG, "Method invocation will be ignored.");
              return;
          }
          if (determineIfCalledFromSeparateScannerProcess()) {
              return;
          }
          synchronized (rangedRegions) {
              rangedRegions.add(region);
          }
          applyChangesToServices(BeaconService.MSG_START_RANGING, region);
      }
docs: Tells the <code>BeaconService</code> to start looking for beacons that match the passed
  <code>Region</code> object, and providing updates on the estimated mDistance every seconds while
  beacons in the Region are visible.  Note that the Region's unique identifier must be retained to
  later call the stopRangingBeaconsInRegion method.
  
  @param region
  @see BeaconManager#setRangeNotifier(RangeNotifier)
  @see BeaconManager#stopRangingBeaconsInRegion(Region region)
  @see RangeNotifier
  @see Region