Type annotations for base spec

.github/workflows/main.yaml

@@ -50,6 +50,10 @@ jobs:
           pip install -e .[test_full]
           pytest -v
 
+      - name: Run Stub Tests
+        shell: bash -l {0}
+        run: stubtest fsspec.spec
+
   win:
     name: pytest-win
     runs-on: windows-2022

README.md

@@ -81,6 +81,11 @@ run and corresponding environment file run a set of tests from the dask
 test suite, and very minimal tests against pandas and zarr from the
 test_downstream.py module in this repo.
 
+### Type Hints
+
+fsspec uses type stub files for type hints instead of inline hints. Use ``stubtest <module>``
+to verify if type stubs are in sync with implementation.
+
 ### Code Formatting
 
 fsspec uses [Black](https://black.readthedocs.io/en/stable) to ensure