diff --git a/src/thd_json/detector/__init__.py b/src/thd_json/detector/__init__.py
index 1f382c233d56ebdf168b538378dc9e05f301a202..1915e931fc9e9a1ffef99b606481080a324ceb8e 100644
--- a/src/thd_json/detector/__init__.py
+++ b/src/thd_json/detector/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/header/__init__.py b/src/thd_json/header/__init__.py
index 4af07ce236d9cbf1f189f46cd4b2b77eb862c2b1..5cae0b3cd170a676e7812cd2c41e0adb15b90b55 100644
--- a/src/thd_json/header/__init__.py
+++ b/src/thd_json/header/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/image/__init__.py b/src/thd_json/image/__init__.py
index 4dd5cb3706ea7d3f2c36811f61443543e135c302..bf065347f96b3daef3d51afac6adb10cc1319304 100644
--- a/src/thd_json/image/__init__.py
+++ b/src/thd_json/image/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/projection/__init__.py b/src/thd_json/projection/__init__.py
index 0c4b663578e3617c5387f1648544b7002543dbfd..8328bdddadc241a1aefae7ac9b0cad2efdccf29a 100644
--- a/src/thd_json/projection/__init__.py
+++ b/src/thd_json/projection/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 from thd_json.header import JsonHeader, generate_header
 from thd_json.projection_geometry import get_projection_geometry_dict
diff --git a/src/thd_json/projection_geometry/__init__.py b/src/thd_json/projection_geometry/__init__.py
index de1571f72f7535c1c49d8064fbf4a3b304b1f565..4e8b0219e23b6a587611bbbbfd8d102979c3351b 100644
--- a/src/thd_json/projection_geometry/__init__.py
+++ b/src/thd_json/projection_geometry/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/projection_matrix/__init__.py b/src/thd_json/projection_matrix/__init__.py
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..6c43ea250f9dd34a0cdb4399c421bfe9cb44e04b 100644
--- a/src/thd_json/projection_matrix/__init__.py
+++ b/src/thd_json/projection_matrix/__init__.py
@@ -0,0 +1 @@
+from __future__ import annotations
\ No newline at end of file
diff --git a/src/thd_json/roi/__init__.py b/src/thd_json/roi/__init__.py
index 06c753435afe956466eaa9cb2df4a11d85a64dda..ff4cd7b19f873041def5ca707148d9021f007840 100644
--- a/src/thd_json/roi/__init__.py
+++ b/src/thd_json/roi/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/source/__init__.py b/src/thd_json/source/__init__.py
index 62e56f51131dcba93fc66a69f0f8453df4ecfb58..afc1b5d3358acd2a98525284b292ed2a0f381fd2 100644
--- a/src/thd_json/source/__init__.py
+++ b/src/thd_json/source/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path
diff --git a/src/thd_json/validation.py b/src/thd_json/validation.py
index 50859cc094f4c00096adccdef5d26b1882d036ec..795ce1d5f2b7d4115dab6e9b1923caca410d77c3 100644
--- a/src/thd_json/validation.py
+++ b/src/thd_json/validation.py
@@ -11,25 +11,23 @@ class Validator:
         print(f"Validator for schema: {json_schema} \nSuffix: {json_suffix}\n")
 
     def file(self, file_path: Path) -> bool:
-        with (
-            open(str(self.json_schema)) as schema_file,
-            open(str(file_path)) as data_file,
-        ):
-            schema = json.load(schema_file)
-            data = json.load(data_file)
-            schema_path = self.json_schema.parent.absolute().as_uri()
-            resolver = RefResolver(base_uri=schema_path, referrer=schema)
+        with open(str(self.json_schema)) as schema_file:
+            with open(str(file_path)) as data_file:
+                schema = json.load(schema_file)
+                data = json.load(data_file)
+                schema_path = self.json_schema.parent.absolute().as_uri()
+                resolver = RefResolver(base_uri=schema_path, referrer=schema)
 
-            try:
-                Draft202012Validator(
-                    schema=schema,
-                    format_checker=Draft202012Validator.FORMAT_CHECKER,
-                    resolver=resolver,
-                ).validate(data)
-                print(f"Validate file: {file_path.parent} / {file_path.name}\n")
+                try:
+                    Draft202012Validator(
+                        schema=schema,
+                        format_checker=Draft202012Validator.FORMAT_CHECKER,
+                        resolver=resolver,
+                    ).validate(data)
+                    print(f"Validate file: {file_path.parent} / {file_path.name}\n")
 
-            except ValidationError as e:
-                print("Validation error:", e)
+                except ValidationError as e:
+                    print("Validation error:", e)
 
         return True
 
diff --git a/src/thd_json/volume/__init__.py b/src/thd_json/volume/__init__.py
index a7237a5939f12b32472c21b1d5a6590bfb7af484..f7146a2f5141e5466d1d957aafa146030b4fbf53 100644
--- a/src/thd_json/volume/__init__.py
+++ b/src/thd_json/volume/__init__.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from thd_json import Validator
 
 from pathlib import Path