diff --git a/examples/02_demonstration/weather/custom_types.midas b/examples/02_demonstration/weather/custom_types.midas
index 2dff64c..d945cab 100644
--- a/examples/02_demonstration/weather/custom_types.midas
+++ b/examples/02_demonstration/weather/custom_types.midas
@@ -38,7 +38,7 @@ alias RawData = Frame[
 
 alias Data = Frame[
     station_id: StationID,
-    timestamp: object,
+    timestamp: Any,
     temperature: Temperature,
     pressure: Pressure,
     humidity: Humidity,
@@ -46,7 +46,7 @@ alias Data = Frame[
 
 alias DataWithHI = Frame[
     station_id: StationID,
-    timestamp: object,
+    timestamp: Any,
     temperature: Temperature,
     pressure: Pressure,
     humidity: Humidity,
@@ -54,7 +54,7 @@ alias DataWithHI = Frame[
 ]
 
 alias DailyAverages = Frame[
-    timestamp: object,
+    timestamp: Any,
     temperature: Mean[Temperature],
     pressure: Mean[Pressure],
     humidity: Mean[Humidity],
diff --git a/examples/02_demonstration/weather/pipeline.py b/examples/02_demonstration/weather/pipeline.py
index 3da4a49..3593f12 100644
--- a/examples/02_demonstration/weather/pipeline.py
+++ b/examples/02_demonstration/weather/pipeline.py
@@ -47,7 +47,7 @@ def daily_avg(df: DataWithHI):
         DailyAverages,
         df.groupby(
             by=[
-                df["station_id"],
+                "station_id",
                 df["timestamp"].dt.day.rename("day"),
             ],
         )