code: @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
      public static Branch getInstance() {
          /* Check if BranchApp is instantiated. */
          if (branchReferral_ == null) {
              PrefHelper.Debug("Branch instance is not created yet. Make sure you have initialised Branch. [Consider Calling getInstance(Context ctx) if you still have issue.]");
          } else if (isAutoSessionMode_) {
              /* Check if Activity life cycle callbacks are set if in auto session mode. */
              if (!isActivityLifeCycleCallbackRegistered_) {
                  PrefHelper.Debug("Branch instance is not properly initialised. Make sure your Application class is extending BranchApp class. " +
                          "If you are not extending BranchApp class make sure you are initialising Branch in your Applications onCreate()");
              }
          }
          return branchReferral_;
      }
docs: <p>Singleton method to return the pre-initialised object of the type {@link Branch}.
  Make sure your app is instantiating {@link BranchApp} before calling this method
  or you have created an instance of Branch already by calling getInstance(Context ctx).</p>
  
  @return An initialised singleton {@link Branch} object