Fix typing and minor issues

tests/test_great_ai.py

@@ -0,0 +1,22 @@
+from asyncio import sleep
+
+import pytest
+from great_ai import GreatAI
+
+
+def test_process_batch() -> None:
+    @GreatAI.create
+    def f(x: int) -> int:
+        return x + 2
+
+    assert [v.output for v in f.process_batch([3, 9, 34])] == [5, 11, 36]
+
+
+@pytest.mark.asyncio
+async def test_process_batch_async() -> None:
+    @GreatAI.create
+    async def f(x: int) -> int:
+        await sleep(0.2)
+        return x + 2
+
+    assert [v.output for v in f.process_batch([3, 9, 34])] == [5, 11, 36]