Changed SeriesGroupBy to return Series (#445)

* update

* updated the generic.pyi

Author: ramvikrams

pandas-stubs/core/groupby/generic.pyi

@@ -67,12 +67,12 @@ class SeriesGroupBy(GroupBy, Generic[S1]):
     def describe(self, **kwargs) -> DataFrame: ...
     def value_counts(
         self,
-        normalize: bool = ...,
+        normalize: Literal[False, True] = ...,
         sort: bool = ...,
         ascending: bool = ...,
         bins=...,
         dropna: bool = ...,
-    ) -> DataFrame: ...
+    ) -> Series: ...
     def count(self) -> Series[int]: ...
     def pct_change(
         self,

tests/test_frame.py

@@ -1942,3 +1942,14 @@ def series_added_in_astype() -> None:
     # GH410
     df = pd.DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
     check(assert_type(df.astype(df.dtypes), pd.DataFrame), pd.DataFrame)
+
+
+def test_series_groupby_and_value_counts() -> None:
+    df = pd.DataFrame(
+        {
+            "Animal": ["Falcon", "Falcon", "Parrot", "Parrot"],
+            "Max Speed": [380, 370, 24, 26],
+        }
+    )
+    c: pd.Series = df.groupby("Animal")["Max Speed"].value_counts()
+    check(assert_type(c, pd.Series), pd.Series)