Flake8 dislikes this kind of typing.

Typing is not my business

src/pyFAI/io/integration_config.py

@@ -502,7 +502,7 @@ def save(self, filename):
             w.write(json.dumps(self.as_dict(), indent=2))
 
     @classmethod
-    def from_file(cls, filename: str) -> WorkerConfig:
+    def from_file(cls, filename: str):
         """load the content of a JSON file and provide a dataclass instance"""
         with open(filename, "r") as f:
             dico = json.loads(f.read())