Add types to pre-commit

pre_commit/languages/docker_image.py

@@ -1,7 +1,13 @@
+from typing import Sequence
+from typing import Tuple
+from typing import TYPE_CHECKING
+
 from pre_commit.languages import helpers
 from pre_commit.languages.docker import assert_docker_available
 from pre_commit.languages.docker import docker_cmd
 
+if TYPE_CHECKING:
+    from pre_commit.repository import Hook
 
 ENVIRONMENT_DIR = None
 get_default_version = helpers.basic_get_default_version
@@ -9,7 +15,11 @@ healthy = helpers.basic_healthy
 install_environment = helpers.no_install
 
 
-def run_hook(hook, file_args, color):  # pragma: windows no cover
+def run_hook(
+        hook: 'Hook',
+        file_args: Sequence[str],
+        color: bool,
+) -> Tuple[int, bytes]:  # pragma: windows no cover
     assert_docker_available()
     cmd = docker_cmd() + hook.cmd
     return helpers.run_xargs(hook, cmd, file_args, color=color)