API: groupby (#95)

Author: jbrockmendel

spec/API_specification/dataframe_api/dataframe_object.py

@@ -359,6 +359,5 @@ def __divmod__(self, other: DataFrame | "Scalar") -> tuple["DataFrame", "DataFra
         Returns
         -------
         DataFrame
-        DataFrame
         """
         ...

spec/API_specification/dataframe_api/groupby_object.py

@@ -0,0 +1,36 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from .dataframe_object import DataFrame
+
+
+class GroupBy:
+    def any(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def all(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def min(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def max(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def sum(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def prod(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def median(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def mean(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def std(self, skipna: bool = True) -> DataFrame:
+        ...
+
+    def var(self, skipna: bool = True) -> DataFrame:
+        ...