Add __all__ for modules beginning with 'h' and 'i' (#7327)

stdlib/io.pyi

@@ -7,6 +7,50 @@ from types import TracebackType
 from typing import IO, Any, BinaryIO, Callable, Iterable, Iterator, TextIO
 from typing_extensions import Literal
 
+if sys.version_info >= (3, 8):
+    __all__ = [
+        "BlockingIOError",
+        "open",
+        "open_code",
+        "IOBase",
+        "RawIOBase",
+        "FileIO",
+        "BytesIO",
+        "StringIO",
+        "BufferedIOBase",
+        "BufferedReader",
+        "BufferedWriter",
+        "BufferedRWPair",
+        "BufferedRandom",
+        "TextIOBase",
+        "TextIOWrapper",
+        "UnsupportedOperation",
+        "SEEK_SET",
+        "SEEK_CUR",
+        "SEEK_END",
+    ]
+else:
+    __all__ = [
+        "BlockingIOError",
+        "open",
+        "IOBase",
+        "RawIOBase",
+        "FileIO",
+        "BytesIO",
+        "StringIO",
+        "BufferedIOBase",
+        "BufferedReader",
+        "BufferedWriter",
+        "BufferedRWPair",
+        "BufferedRandom",
+        "TextIOBase",
+        "TextIOWrapper",
+        "UnsupportedOperation",
+        "SEEK_SET",
+        "SEEK_CUR",
+        "SEEK_END",
+    ]
+
 DEFAULT_BUFFER_SIZE: Literal[8192]
 
 SEEK_SET: Literal[0]