diff --git a/core/lib/Drupal/Component/Utility/SafeMarkup.php b/core/lib/Drupal/Component/Utility/SafeMarkup.php
index 4f11c49..60b3b35 100644
--- a/core/lib/Drupal/Component/Utility/SafeMarkup.php
+++ b/core/lib/Drupal/Component/Utility/SafeMarkup.php
@@ -85,7 +85,18 @@ public static function set($string, $strategy = 'html') {
   }
 
   /**
-   * @todo
+   * Remove a string from the list of safe strings.
+   *
+   * This can be used when preparing to actually print a string to conserve
+   * memory.
+   *
+   * @param string $string
+   *   The string to be removed from the safe list.
+   * @param string $strategy
+   *   The escaping strategy used for this string. Two values are supported
+   *   by default:
+   *   - 'html': (default) The string is safe for use in HTML code.
+   *   - 'all': The string is safe for all use cases.
    */
   public static function remove($string, $strategy = 'html') {
     $string = (string) $string;
diff --git a/core/modules/system/src/Tests/Theme/FunctionsTest.php b/core/modules/system/src/Tests/Theme/FunctionsTest.php
index 25721bb..c2301cb 100644
--- a/core/modules/system/src/Tests/Theme/FunctionsTest.php
+++ b/core/modules/system/src/Tests/Theme/FunctionsTest.php
@@ -167,6 +167,9 @@ function testItemList() {
     $this->assertThemeOutput('item_list', $variables, $expected);
   }
 
+  /**
+   * Helper to set up variables for theme_links().
+   */
   protected function getVariables() {
     // Verify that a list of links is properly rendered.
     $variables = array();