diff --git a/build.py b/build.py
index 507985d..d086637 100644
--- a/build.py
+++ b/build.py
@@ -33,7 +33,7 @@ default_task = "dev"
 name = "ddadevops"
 MODULE = "not-used"
 PROJECT_ROOT_PATH = "."
-version = "4.0.10-SNAPSHOT"
+version = "4.0.10-dev1"
 summary = "tools to support builds combining gopass, terraform, dda-pallet, aws & hetzner-cloud"
 description = __doc__
 authors = [Author("meissa GmbH", "buero@meissa-gmbh.de")]
diff --git a/src/main/python/ddadevops/domain/build_file.py b/src/main/python/ddadevops/domain/build_file.py
index 30ce8fe..350a4a9 100644
--- a/src/main/python/ddadevops/domain/build_file.py
+++ b/src/main/python/ddadevops/domain/build_file.py
@@ -1,6 +1,7 @@
 import json
 import re
 from enum import Enum
+from typing import Optional
 from pathlib import Path
 from .common import Validateable
 from .version import Version
@@ -26,9 +27,10 @@ class BuildFile(Validateable):
             result += [f"Suffix {self.file_path} is unknown."]
         return result
 
-    def build_file_type(self):
+    def build_file_type(self) -> Optional[BuildFileType]:
+        result: Optional[BuildFileType] = None
         if not self.file_path:
-            return None
+            return result
         config_file_type = self.file_path.suffix
         match config_file_type:
             case ".json":
@@ -115,7 +117,7 @@ class BuildFile(Validateable):
         except:
             raise Exception(f"Version not found in file {self.file_path}")
 
-    def get_default_suffix(self) -> Version:
+    def get_default_suffix(self) -> str:
         result = "SNAPSHOT"
         match self.build_file_type():
             case BuildFileType.PYTHON:
diff --git a/src/main/python/ddadevops/domain/version.py b/src/main/python/ddadevops/domain/version.py
index da777f4..2f2096a 100644
--- a/src/main/python/ddadevops/domain/version.py
+++ b/src/main/python/ddadevops/domain/version.py
@@ -69,38 +69,73 @@ class Version(Validateable):
         new_version_list = self.version_list.copy()
         if self.is_snapshot():
             return Version(
-                new_version_list, self.default_snapshot_suffix, snapshot_suffix=tmp_snapshot_suffix, version_str=None
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=tmp_snapshot_suffix,
+                version_str=None,
             )
         else:
             new_version_list[2] += 1
             return Version(
-                new_version_list, self.default_snapshot_suffix, snapshot_suffix=tmp_snapshot_suffix, version_str=None
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=tmp_snapshot_suffix,
+                version_str=None,
             )
 
     def create_patch(self):
         new_version_list = self.version_list.copy()
         if self.is_snapshot():
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )
         else:
             new_version_list[2] += 1
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )
 
     def create_minor(self):
         new_version_list = self.version_list.copy()
         if self.is_snapshot() and new_version_list[2] == 0:
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )
         else:
             new_version_list[2] = 0
             new_version_list[1] += 1
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )
 
     def create_major(self):
         new_version_list = self.version_list.copy()
         if self.is_snapshot() and new_version_list[2] == 0 and new_version_list[1] == 0:
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )
         else:
             new_version_list[2] = 0
             new_version_list[1] = 0
             new_version_list[0] += 1
-            return Version(new_version_list, self.default_snapshot_suffix, snapshot_suffix=None, version_str=None)
-
+            return Version(
+                new_version_list,
+                self.default_snapshot_suffix,
+                snapshot_suffix=None,
+                version_str=None,
+            )