1 files changed, 27 insertions, 12 deletions
diff --git a/Lib/importlib/resources/abc.py b/Lib/importlib/resources/abc.py
index e9efdab..0b7bfdc 100644
--- a/Lib/importlib/resources/abc.py
+++ b/Lib/importlib/resources/abc.py
@@ -1,6 +1,14 @@
 import abc
-from typing import BinaryIO, Iterable, Text
+import io
+import os
+from typing import Any, BinaryIO, Iterable, Iterator, NoReturn, Text, Optional
 from typing import runtime_checkable, Protocol
+from typing import Union
+
+
+StrPath = Union[str, os.PathLike[str]]
+
+__all__ = ["ResourceReader", "Traversable", "TraversableResources"]
 
 
 class ResourceReader(metaclass=abc.ABCMeta):
@@ -50,22 +58,25 @@ class Traversable(Protocol):
     """
     An object with a subset of pathlib.Path methods suitable for
     traversing directories and opening files.
+
+    Any exceptions that occur when accessing the backing resource
+    may propagate unaltered.
     """
 
     @abc.abstractmethod
-    def iterdir(self):
+    def iterdir(self) -> Iterator["Traversable"]:
         """
         Yield Traversable objects in self
         """
 
-    def read_bytes(self):
+    def read_bytes(self) -> bytes:
         """
         Read contents of self as bytes
         """
         with self.open('rb') as strm:
             return strm.read()
 
-    def read_text(self, encoding=None):
+    def read_text(self, encoding: Optional[str] = None) -> str:
         """
         Read contents of self as text
         """
@@ -85,12 +96,16 @@ class Traversable(Protocol):
         """
 
     @abc.abstractmethod
-    def joinpath(self, child):
+    def joinpath(self, *descendants: StrPath) -> "Traversable":
         """
-        Return Traversable child in self
+        Return Traversable resolved with any descendants applied.
+
+        Each descendant should be a path segment relative to self
+        and each may contain multiple levels separated by
+        ``posixpath.sep`` (``/``).
         """
 
-    def __truediv__(self, child):
+    def __truediv__(self, child: StrPath) -> "Traversable":
         """
         Return Traversable child in self
         """
@@ -120,17 +135,17 @@ class TraversableResources(ResourceReader):
     """
 
     @abc.abstractmethod
-    def files(self):
+    def files(self) -> "Traversable":
         """Return a Traversable object for the loaded package."""
 
-    def open_resource(self, resource):
+    def open_resource(self, resource: StrPath) -> io.BufferedReader:
         return self.files().joinpath(resource).open('rb')
 
-    def resource_path(self, resource):
+    def resource_path(self, resource: Any) -> NoReturn:
         raise FileNotFoundError(resource)
 
-    def is_resource(self, path):
+    def is_resource(self, path: StrPath) -> bool:
         return self.files().joinpath(path).is_file()
 
-    def contents(self):
+    def contents(self) -> Iterator[str]:
         return (item.name for item in self.files().iterdir())