+    def get_testcases(self, include_onlymatching=False):
+        t = getattr(self, '_TEST', None)
+        if t:
+            assert not hasattr(self, '_TESTS'), \
+                '%s has _TEST and _TESTS' % type(self).__name__
+            tests = [t]
+        else:
+            tests = getattr(self, '_TESTS', [])
+        for t in tests:
+            if not include_onlymatching and t.get('only_matching', False):
+                continue
+            t['name'] = type(self).__name__[:-len('IE')]
+            yield t
+
+    def is_suitable(self, age_limit):
+        """ Test whether the extractor is generally suitable for the given
+        age limit (i.e. pornographic sites are not, all others usually are) """
+
+        any_restricted = False
+        for tc in self.get_testcases(include_onlymatching=False):
+            if 'playlist' in tc:
+                tc = tc['playlist'][0]
+            is_restricted = age_restricted(
+                tc.get('info_dict', {}).get('age_limit'), age_limit)
+            if not is_restricted:
+                return True
+            any_restricted = any_restricted or is_restricted
+        return not any_restricted
+
+    def extract_subtitles(self, *args, **kwargs):
+        if (self._downloader.params.get('writesubtitles', False) or
+                self._downloader.params.get('listsubtitles')):
+            return self._get_subtitles(*args, **kwargs)
+        return {}
+
+    def _get_subtitles(self, *args, **kwargs):
+        raise NotImplementedError("This method must be implemented by subclasses")
+
+    def extract_automatic_captions(self, *args, **kwargs):
+        if (self._downloader.params.get('writeautomaticsub', False) or
+                self._downloader.params.get('listsubtitles')):
+            return self._get_automatic_captions(*args, **kwargs)
+        return {}
+
+    def _get_automatic_captions(self, *args, **kwargs):
+        raise NotImplementedError("This method must be implemented by subclasses")
+