Add types to pre-commit

pre_commit/languages/fail.py

@@ -1,5 +1,11 @@
+from typing import Sequence
+from typing import Tuple
+from typing import TYPE_CHECKING
+
 from pre_commit.languages import helpers
 
+if TYPE_CHECKING:
+    from pre_commit.repository import Hook
 
 ENVIRONMENT_DIR = None
 get_default_version = helpers.basic_get_default_version
@@ -7,7 +13,11 @@ healthy = helpers.basic_healthy
 install_environment = helpers.no_install
 
 
-def run_hook(hook, file_args, color):
+def run_hook(
+        hook: 'Hook',
+        file_args: Sequence[str],
+        color: bool,
+) -> Tuple[int, bytes]:
     out = hook.entry.encode('UTF-8') + b'\n\n'
     out += b'\n'.join(f.encode('UTF-8') for f in file_args) + b'\n'
     return 1, out