Fix PYRE_FIXME issue in fbcode/core_stats/balance/sample_class.py (#299)

Summary: Pull Request resolved: #299

Reviewed By: talgalili

Differential Revision: D91468929

fbshipit-source-id: 628901a45e9d98bc4231d119c455d68c04e785d7

Author: generatedunixname893464919433493

balance/sample_class.py

@@ -130,8 +130,7 @@ class Sample:
     weight_column = None
     # pyre-fixme[4]: Attributes are initialized in from_frame()
     _links = None
-    # pyre-fixme[4]: Attributes are initialized in from_frame()
-    _adjustment_model = None
+    _adjustment_model: Dict[str, Any] | None = None
     # pyre-fixme[4]: Attributes are initialized in from_frame()
     _df_dtypes = None