Fix baselines utils pyre fix me issues

Differential Revision: D67706854

Author: Vivek Miglani

captum/attr/_utils/baselines.py

@@ -2,10 +2,12 @@
 
 # pyre-strict
 import random
-from typing import Any, Dict, List, Tuple, Union
+from typing import Any, Dict, Generic, List, Tuple, TypeVar, Union
 
+GenericBaselineType = TypeVar("GenericBaselineType")
 
-class ProductBaselines:
+
+class ProductBaselines(Generic[GenericBaselineType]):
     """
     A Callable Baselines class that returns a sample from the Cartesian product of
     the inputs' available baselines.
@@ -22,10 +24,9 @@ class ProductBaselines:
 
     def __init__(
         self,
-        # pyre-fixme[2]: Parameter annotation cannot contain `Any`.
         baseline_values: Union[
-            List[List[Any]],
-            Dict[Union[str, Tuple[str, ...]], List[Any]],
+            List[List[GenericBaselineType]],
+            Dict[Union[str, Tuple[str, ...]], List[GenericBaselineType]],
         ],
     ) -> None:
         if isinstance(baseline_values, dict):
@@ -38,9 +39,10 @@ def __init__(
         self.dict_keys = dict_keys
         self.baseline_values = baseline_values
 
-    # pyre-fixme[3]: Return annotation cannot contain `Any`.
-    def sample(self) -> Union[List[Any], Dict[str, Any]]:
-        baselines = [
+    def sample(
+        self,
+    ) -> Union[List[GenericBaselineType], Dict[str, GenericBaselineType]]:
+        baselines: List[GenericBaselineType] = [
             random.choice(baseline_list) for baseline_list in self.baseline_values
         ]
 
@@ -50,15 +52,18 @@ def sample(self) -> Union[List[Any], Dict[str, Any]]:
         dict_baselines = {}
         for key, val in zip(self.dict_keys, baselines):
             if not isinstance(key, tuple):
-                key, val = (key,), (val,)
+                key_tuple, val_tuple = (key,), (val,)
+            else:
+                key_tuple, val_tuple = key, val
 
-            for k, v in zip(key, val):
+            for k, v in zip(key_tuple, val_tuple):
                 dict_baselines[k] = v
 
         return dict_baselines
 
-    # pyre-fixme[3]: Return annotation cannot contain `Any`.
-    def __call__(self) -> Union[List[Any], Dict[str, Any]]:
+    def __call__(
+        self,
+    ) -> Union[List[GenericBaselineType], Dict[str, GenericBaselineType]]:
         """
         Returns: