Annotate dunder functions

Summary: Annotate the (return type of the) following dunder functions across the codebase: `__init__()`, `__len__()`, `__getitem__()`

Reviewed By: nikhilaravi

Differential Revision: D29001801

fbshipit-source-id: 928d9e1c417ffe01ab8c0445311287786e997c7c

projects/nerf/nerf/dataset.py

@@ -36,7 +36,7 @@ class ListDataset(Dataset):
     A simple dataset made of a list of entries.
     """
 
-    def __init__(self, entries: List):
+    def __init__(self, entries: List) -> None:
         """
         Args:
             entries: The list of dataset entries.
@@ -45,7 +45,7 @@ class ListDataset(Dataset):
 
     def __len__(
         self,
-    ):
+    ) -> int:
         return len(self._entries)
 
     def __getitem__(self, index):

projects/nerf/nerf/stats.py

@@ -22,7 +22,7 @@ class AverageMeter:
     Tracks the exact history of the added values in every epoch.
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         """
         Initialize the structure with empty history and zero-ed moving average.
         """
@@ -110,7 +110,7 @@ class Stats:
         verbose: bool = False,
         epoch: int = -1,
         plot_file: Optional[str] = None,
-    ):
+    ) -> None:
         """
         Args:
             log_vars: The list of variable names to be logged.