twitter: use import_source and proper merging for tweets from different sources

+ use proper datetime_aware for created_at

my/twitter/common.py

@@ -1,12 +1,21 @@
+from my.core import __NOT_HPI_MODULE__
+
 from itertools import chain
+from typing import Iterator, Any
 
 from more_itertools import unique_everseen
 
-from ..core import warn_if_empty, __NOT_HPI_MODULE__
 
+# TODO add proper Protocol for Tweet
+Tweet = Any
+
+
+from my.core import warn_if_empty, Res
 @warn_if_empty
-def merge_tweets(*sources):
-    yield from unique_everseen(
-        chain(*sources),
-        key=lambda t: t.id_str,
-    )
+def merge_tweets(*sources: Iterator[Res[Tweet]]) -> Iterator[Res[Tweet]]:
+    def key(r: Res[Tweet]):
+        if isinstance(r, Exception):
+            return str(r)
+        else:
+            return r.id_str
+    yield from unique_everseen(chain(*sources), key=key)