fix: fix 'assignment-from-no-return' for pylint

.pylintrc

@@ -3,6 +3,7 @@
 [MESSAGES CONTROL]
 disable=all
 enable=anomalous-backslash-in-string,
+        assignment-from-no-return,
         bare-except,
         broad-exception-caught,
         dangerous-default-value,

src/wuttjamaican/batch.py

@@ -348,7 +348,7 @@ class BatchHandler(GenericHandler):
         * :attr:`~wuttjamaican.db.model.batch.BatchMixin.status_text`
         """
 
-    def why_not_execute(self, batch, user=None, **kwargs):
+    def why_not_execute(self, batch, user=None, **kwargs): # pylint: disable=unused-argument
         """
         Returns text indicating the reason (if any) that a given batch
         should *not* be executed.
@@ -385,6 +385,7 @@ class BatchHandler(GenericHandler):
         raise a ``RuntimeError`` if text was returned.  This is done
         out of safety, to avoid relying on the user interface.
         """
+        return None
 
     def describe_execution(self, batch, user=None, **kwargs):
         """
@@ -476,7 +477,7 @@ class BatchHandler(GenericHandler):
         batch.executed_by = user
         return result
 
-    def execute(self, batch, user=None, progress=None, **kwargs):
+    def execute(self, batch, user=None, progress=None, **kwargs): # pylint: disable=unused-argument
         """
         Execute the given batch.
 
@@ -502,6 +503,7 @@ class BatchHandler(GenericHandler):
            whatever it likes, in which case that will be also returned
            to the caller from :meth:`do_execute()`.
         """
+        return None
 
     def do_delete(self, batch, user, dry_run=False, progress=None, **kwargs): # pylint: disable=unused-argument
         """