diff --git a/src/galaxy/api/plugin.py b/src/galaxy/api/plugin.py
index 5fd778e..b2704e8 100644
--- a/src/galaxy/api/plugin.py
+++ b/src/galaxy/api/plugin.py
@@ -4,7 +4,7 @@ import json
 import logging
 import sys
 from enum import Enum
-from typing import Any, Dict, List, Optional, Set, Union
+from typing import Any, Dict, List, Optional, Set, Union, AsyncGenerator
 
 from galaxy.api.consts import Feature, OSCompatibility
 from galaxy.api.errors import ImportInProgress, UnknownError
@@ -42,7 +42,8 @@ class Importer:
         notification_success,
         notification_failure,
         notification_finished,
-        complete
+        complete,
+        yielding=False
     ):
         self._task_manager = task_manger
         self._name = name
@@ -54,39 +55,44 @@ class Importer:
         self._complete = complete
 
         self._import_in_progress = False
+        self._yielding = yielding
+
+    async def _import_element(self, id_, context_):
+        try:
+            if self._yielding:
+                async for element in self._get(id_, context_):
+                    self._notification_success(id_, element)
+            else:
+                element = await self._get(id_, context_)
+                self._notification_success(id_, element)
+        except ApplicationError as error:
+            self._notification_failure(id_, error)
+        except asyncio.CancelledError:
+            pass
+        except Exception:
+            logger.exception("Unexpected exception raised in %s importer", self._name)
+            self._notification_failure(id_, UnknownError())
+
+    async def _import_elements(self, ids_, context_):
+        try:
+            imports = [self._import_element(id_, context_) for id_ in ids_]
+            await asyncio.gather(*imports)
+            self._notification_finished()
+            self._complete()
+        except asyncio.CancelledError:
+            logger.debug("Importing %s cancelled", self._name)
+        finally:
+            self._import_in_progress = False
 
     async def start(self, ids):
         if self._import_in_progress:
             raise ImportInProgress()
 
-        async def import_element(id_, context_):
-            try:
-                element = await self._get(id_, context_)
-                self._notification_success(id_, element)
-            except ApplicationError as error:
-                self._notification_failure(id_, error)
-            except asyncio.CancelledError:
-                pass
-            except Exception:
-                logger.exception("Unexpected exception raised in %s importer", self._name)
-                self._notification_failure(id_, UnknownError())
-
-        async def import_elements(ids_, context_):
-            try:
-                imports = [import_element(id_, context_) for id_ in ids_]
-                await asyncio.gather(*imports)
-                self._notification_finished()
-                self._complete()
-            except asyncio.CancelledError:
-                logger.debug("Importing %s cancelled", self._name)
-            finally:
-                self._import_in_progress = False
-
         self._import_in_progress = True
         try:
             context = await self._prepare_context(ids)
             self._task_manager.create_task(
-                import_elements(ids, context),
+                self._import_elements(ids, context),
                 "{} import".format(self._name),
                 handle_exceptions=False
             )
@@ -185,7 +191,8 @@ class Plugin:
             self._subscription_games_import_success,
             self._subscription_games_import_failure,
             self._subscription_games_import_finished,
-            self.subscription_games_import_complete
+            self.subscription_games_import_complete,
+            yielding=True
         )
 
         # internal
@@ -1122,11 +1129,25 @@ class Plugin:
         """
         return None
 
-    async def get_subscription_games(self, subscription_name: str, context: Any) -> Optional[List[SubscriptionGame]]:
-        """Override this method to return list of subscription games in a given subscription.
+    async def get_subscription_games(self, subscription_name: str, context: Any) -> AsyncGenerator[List[SubscriptionGame],None]:
+        """Override this method to return SubscriptionGames for a given subscription.
+        This method should `yield` results from a list of SubscriptionGames
 
         :param context: the value returned from :meth:`prepare_subscription_games_context`
-        :return: List of subscription games or `None` if list cannot be determined.
+        :return yield List of subscription games.
+
+        .. code-block:: python
+            :linenos:
+
+            async def get_sub_games(sub_name: str, context: Any):
+                for i in range(10):
+                    try:
+                        games_page = await _get_subs_from_backend(sub_name, i)
+                    except KeyError:
+                        print('no more chunk pages for', sub_name)
+                        return
+                    yield [SubGame(game['game_id'], game['game_title']) for game in games_page]
+
         """
         raise NotImplementedError()
 
diff --git a/src/galaxy/unittest/mock.py b/src/galaxy/unittest/mock.py
index da2e033..f3b9855 100644
--- a/src/galaxy/unittest/mock.py
+++ b/src/galaxy/unittest/mock.py
@@ -1,7 +1,6 @@
 import asyncio
 from unittest.mock import MagicMock
 
-
 class AsyncMock(MagicMock):
     """
     .. deprecated:: 0.45