Stricter type-checking for fsspec.caching and fsspec.utils

Author: alanhdu

setup.cfg

@@ -52,3 +52,10 @@ warn_unused_ignores = True
 
 # don't bother type-checking test_*.py or conftest.py files
 exclude = (test_.*|conftest)\.py$
+
+# TODO: turn on globally once we type enough of fsspec
+[mypy-fsspec.caching]
+check_untyped_defs = True
+
+[mypy-fsspec.utils]
+check_untyped_defs = True