Add types to pre-commit

pre_commit/prefix.py

@@ -1,16 +1,17 @@
-import collections
 import os.path
+from typing import NamedTuple
+from typing import Tuple
 
 
-class Prefix(collections.namedtuple('Prefix', ('prefix_dir',))):
-    __slots__ = ()
+class Prefix(NamedTuple):
+    prefix_dir: str
 
-    def path(self, *parts):
+    def path(self, *parts: str) -> str:
         return os.path.normpath(os.path.join(self.prefix_dir, *parts))
 
-    def exists(self, *parts):
+    def exists(self, *parts: str) -> bool:
         return os.path.exists(self.path(*parts))
 
-    def star(self, end):
+    def star(self, end: str) -> Tuple[str, ...]:
         paths = os.listdir(self.prefix_dir)
         return tuple(path for path in paths if path.endswith(end))