assertToCEntryIsCorrectlyTranslated example

$build = $bm->bookTreeOutput($bm->bookTreeAllData($bid));
      $items = $build['#items'];
      $this->assertBookItemIsCorrectlyTranslated($items[$bid], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 1], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 1]['below'][$bid + 3], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 1]['below'][$bid + 4], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 2], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 2]['below'][$bid + 5], $langcode);
      $this->assertBookItemIsCorrectlyTranslated($items[$bid]['below'][$bid + 2]['below'][$bid + 6], $langcode);
      $toc = $bm->getTableOfContents($bid, 4);
      // Root entry does not have an indent.       $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid, '');
      // The direct children of the root have one indent.       $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 1, '--');
      $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 2, '--');
      // Their children have two indents.       $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 3, '----');
      $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 4, '----');
      $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 5, '----');
      $this->assertToCEntryIsCorrectlyTranslated($toc, $langcode, $bid + 6, '----');
      // $bid might be a string.       $this->assertSame([$bid + 0, $bid + 1, $bid + 3, $bid + 4, $bid + 2, $bid + 5, $bid + 6], array_keys($toc));
    }
  }