code: @SuppressWarnings("WeakerAccess")
      @UiThread
      public boolean popToTag(@NonNull String tag, @Nullable ControllerChangeHandler changeHandler) {
          ThreadUtils.ensureMainThread();
  
          for (RouterTransaction transaction : backstack) {
              if (tag.equals(transaction.tag())) {
                  popToTransaction(transaction, changeHandler);
                  return true;
              }
          }
          return false;
      }
docs: Pops all {@link Controller}s until the {@link Controller} with the passed tag is at the top
  
  @param tag           The tag being popped to
  @param changeHandler The {@link ControllerChangeHandler} to handle this transaction
  @return Whether or not the {@link Controller} with the passed tag is now at the top