Contributed stubs for filelock package (#4424)

Co-authored-by: Eric Traut <erictr@microsoft.com>

third_party/3/filelock/__init__.pyi

@@ -0,0 +1,54 @@
+import sys
+from logging import Logger
+from types import TracebackType
+from typing import Optional, Type, Union
+
+def logger() -> Logger: ...
+
+class Timeout(TimeoutError):
+    def __init__(self, lock_file: str) -> None: ...
+    def __str__(self) -> str: ...
+
+class _Acquire_ReturnProxy:
+    def __init__(self, lock: str) -> None: ...
+    def __enter__(self) -> str: ...
+    def __exit__(
+        self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], traceback: Optional[TracebackType]
+    ) -> None: ...
+
+class BaseFileLock:
+    def __init__(self, lock_file: str, timeout: Union[float, int, str] = ...) -> None: ...
+    @property
+    def lock_file(self) -> str: ...
+    @property
+    def timeout(self) -> float: ...
+    @timeout.setter
+    def timeout(self, value: Union[int, str, float]) -> None: ...
+    @property
+    def is_locked(self) -> bool: ...
+    def acquire(self, timeout: Optional[float] = ..., poll_intervall: float = ...) -> _Acquire_ReturnProxy: ...
+    def release(self, force: bool = ...) -> None: ...
+    def __enter__(self) -> BaseFileLock: ...
+    def __exit__(
+        self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], traceback: Optional[TracebackType]
+    ) -> None: ...
+    def __del__(self) -> None: ...
+
+class WindowsFileLock(BaseFileLock):
+    def _acquire(self) -> None: ...
+    def _release(self) -> None: ...
+
+class UnixFileLock(BaseFileLock):
+    def _acquire(self) -> None: ...
+    def _release(self) -> None: ...
+
+class SoftFileLock(BaseFileLock):
+    def _acquire(self) -> None: ...
+    def _release(self) -> None: ...
+
+if sys.platform == "win32":
+    FileLock = WindowsFileLock
+elif sys.platform == "linux" or sys.platform == "darwin":
+    FileLock = UnixFileLock
+else:
+    FileLock = SoftFileLock