cloudpickle isinstance() (#487)

* cloudpickle isinstance()

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update backend.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: jan-janssen

executorlib/cache/backend.py

@@ -18,11 +18,11 @@ def backend_load_file(file_name: str) -> dict:
     """
     apply_dict = load(file_name=file_name)
     apply_dict["args"] = [
-        arg if not isinstance(arg, FutureItem) else arg.result()
+        arg if not _isinstance(arg, FutureItem) else arg.result()
         for arg in apply_dict["args"]
     ]
     apply_dict["kwargs"] = {
-        key: arg if not isinstance(arg, FutureItem) else arg.result()
+        key: arg if not _isinstance(arg, FutureItem) else arg.result()
         for key, arg in apply_dict["kwargs"].items()
     }
     return apply_dict
@@ -62,3 +62,7 @@ def backend_execute_task_in_file(file_name: str) -> None:
         file_name=file_name,
         output=result,
     )
+
+
+def _isinstance(obj: Any, cls: type) -> bool:
+    return str(obj.__class__) == str(cls)