From 2c4205d4bac43d10605668896a0bcbd645076a9f Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Fri, 7 Mar 2025 18:47:09 +0100
Subject: [PATCH 1/9] Test for membership should be not in

---
 sigma/validation.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sigma/validation.py b/sigma/validation.py
index 03625910..111647b9 100644
--- a/sigma/validation.py
+++ b/sigma/validation.py
@@ -132,7 +132,7 @@ def validate_rule(self, rule: SigmaRule) -> List[SigmaValidationIssue]:
         issues: List[SigmaValidationIssue] = []
         exclusions = self.exclusions[rule.id]
         for validator in self.validators:
-            if not validator.__class__ in exclusions:  # Skip if validator is excluded for this rule
+            if validator.__class__ not in exclusions:  # Skip if validator is excluded for this rule
                 issues.extend(validator.validate(rule))
         return issues
 

From e7be9649810796871eb8bc4ad4c940412b572291 Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:06:51 +0100
Subject: [PATCH 2/9] fix: linting issues

---
 sigma/rule/attributes.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sigma/rule/attributes.py b/sigma/rule/attributes.py
index f27f9282..4a0cdda6 100644
--- a/sigma/rule/attributes.py
+++ b/sigma/rule/attributes.py
@@ -1,5 +1,5 @@
 from dataclasses import dataclass, field
-from typing import Any, Dict, Optional, List, Type
+from typing import Any, Dict, Optional, List
 from uuid import UUID
 from enum import Enum, auto
 import sigma.exceptions as sigma_exceptions
@@ -128,7 +128,7 @@ def from_dict(cls, value: Dict[str, str]) -> "SigmaRelatedItem":
         try:
             id = UUID(value["id"])
         except ValueError:
-            raise sigma_exceptions.SigmaRelatedError(f"Sigma related identifier must be an UUID")
+            raise sigma_exceptions.SigmaRelatedError("Sigma related identifier must be an UUID")
 
         try:
             type = SigmaRelatedType[value["type"].upper()]
@@ -153,9 +153,9 @@ def from_dict(cls, val: List[Dict[str, str]]) -> "SigmaRelated":
 
         list_ret: List[SigmaRelatedItem] = []
         for v in val:
-            if not "id" in v.keys():
+            if "id" not in v.keys():
                 raise sigma_exceptions.SigmaRelatedError("Sigma related must have an id field")
-            elif not "type" in v.keys():
+            elif "type" not in v.keys():
                 raise sigma_exceptions.SigmaRelatedError("Sigma related must have a type field")
             else:
                 list_ret.append(SigmaRelatedItem.from_dict(v))  # should rise the SigmaRelatedError

From 3c68f1905fb84ba7186683d44f97f372f85885f9 Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:12:44 +0100
Subject: [PATCH 3/9] fix: removed duplication of post_init()

---
 sigma/processing/pipeline.py | 30 ------------------------------
 1 file changed, 30 deletions(-)

diff --git a/sigma/processing/pipeline.py b/sigma/processing/pipeline.py
index 9365cc16..dbc69dd2 100644
--- a/sigma/processing/pipeline.py
+++ b/sigma/processing/pipeline.py
@@ -238,21 +238,6 @@ def _check_conditions(
                     f"{name} '{str(condition)}' is not a {expected_condition_class.__name__}"
                 )
 
-    def __post_init__(self):
-        self._check_conditions(
-            "rule_condition_expression",
-            "rule_condition_linking",
-            "rule_conditions",
-            RuleProcessingCondition,
-            "Rule condition",
-        )
-        self.transformation.set_processing_item(
-            self
-        )  # set processing item in transformation object after it is instantiated
-        self._resolve_condition_expression(
-            self.rule_condition_expression, self.rule_conditions, "Rule condition"
-        )
-
     def _resolve_condition_expression(
         self,
         expr: Optional[ConditionExpression],
@@ -352,21 +337,6 @@ def _check_conditions(
                     f"{name} '{str(condition)}' is not a {expected_condition_class.__name__}"
                 )
 
-    def __post_init__(self):
-        self._check_conditions(
-            "rule_condition_expression",
-            "rule_condition_linking",
-            "rule_conditions",
-            RuleProcessingCondition,
-            "Rule condition",
-        )
-        self.transformation.set_processing_item(
-            self
-        )  # set processing item in transformation object after it is instantiated
-        self._resolve_condition_expression(
-            self.rule_condition_expression, self.rule_conditions, "Rule condition"
-        )
-
     def _resolve_condition_expression(
         self,
         expr: Optional[ConditionExpression],

From 076b09e8d7effe89551df8139da7da281461001c Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:12:54 +0100
Subject: [PATCH 4/9] fix: linting issues

---
 sigma/processing/pipeline.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sigma/processing/pipeline.py b/sigma/processing/pipeline.py
index dbc69dd2..88047691 100644
--- a/sigma/processing/pipeline.py
+++ b/sigma/processing/pipeline.py
@@ -486,7 +486,7 @@ def set_pipeline(self, pipeline: "ProcessingPipeline") -> None:
         if self._pipeline is None:
             self._pipeline = pipeline
         else:
-            raise SigmaProcessingItemError(f"Pipeline for processing item was already set.")
+            raise SigmaProcessingItemError("Pipeline for processing item was already set.")
 
         self.transformation.set_pipeline(pipeline)
         for rule_condition in self.rule_conditions:
@@ -875,7 +875,7 @@ def from_yaml(cls, processing_pipeline: str) -> "ProcessingPipeline":
         try:
             parsed_pipeline = yaml.safe_load(processing_pipeline)
         except yaml.parser.ParserError as e:
-            raise SigmaPipelineParsingError(f"Error in parsing of a Sigma processing pipeline")
+            raise SigmaPipelineParsingError("Error in parsing of a Sigma processing pipeline")
         return cls.from_dict(parsed_pipeline)
 
     def apply(

From 12bab9024a1a291d9f8aed6bccd6540c42c8356a Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:22:51 +0100
Subject: [PATCH 5/9] fix: linting issues

---
 sigma/processing/conditions/base.py             | 3 +--
 sigma/processing/conditions/fields.py           | 1 -
 sigma/processing/conditions/rule.py             | 3 +--
 sigma/processing/conditions/state.py            | 1 -
 sigma/processing/conditions/values.py           | 1 -
 sigma/processing/finalization.py                | 4 ++--
 sigma/processing/transformations/base.py        | 5 +----
 sigma/processing/transformations/condition.py   | 3 ---
 sigma/processing/transformations/failure.py     | 1 -
 sigma/processing/transformations/fields.py      | 1 -
 sigma/processing/transformations/placeholder.py | 3 +--
 sigma/processing/transformations/rule.py        | 4 ----
 sigma/processing/transformations/state.py       | 1 -
 13 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/sigma/processing/conditions/base.py b/sigma/processing/conditions/base.py
index eb08bbe6..326eb26d 100644
--- a/sigma/processing/conditions/base.py
+++ b/sigma/processing/conditions/base.py
@@ -13,7 +13,6 @@
 from sigma.exceptions import (
     SigmaConfigurationError,
     SigmaProcessingItemError,
-    SigmaRegularExpressionError,
 )
 
 
@@ -29,7 +28,7 @@ def set_pipeline(self, pipeline: "sigma.processing.pipeline.ProcessingPipeline")
         if self._pipeline is None:
             self._pipeline = pipeline
         else:
-            raise SigmaProcessingItemError(f"Pipeline for condition was already set.")
+            raise SigmaProcessingItemError("Pipeline for condition was already set.")
 
     def _clear_pipeline(self) -> None:
         self._pipeline = None
diff --git a/sigma/processing/conditions/fields.py b/sigma/processing/conditions/fields.py
index dc86468f..c3ca6436 100644
--- a/sigma/processing/conditions/fields.py
+++ b/sigma/processing/conditions/fields.py
@@ -1,6 +1,5 @@
 from dataclasses import dataclass, field
 
-import sigma
 from sigma.processing.conditions.base import FieldNameProcessingCondition
 from typing import List, Pattern, Literal, Optional
 import re
diff --git a/sigma/processing/conditions/rule.py b/sigma/processing/conditions/rule.py
index 81c13785..30ad2e91 100644
--- a/sigma/processing/conditions/rule.py
+++ b/sigma/processing/conditions/rule.py
@@ -2,7 +2,6 @@
 from datetime import date
 from uuid import UUID
 
-import sigma
 from sigma.correlations import SigmaCorrelationRule
 from sigma.processing.conditions.base import (
     RuleDetectionItemCondition,
@@ -91,7 +90,7 @@ def find_detection_item(self, detection: Union[SigmaDetectionItem, SigmaDetectio
                 detection.field is not None
                 and detection.field == self.field
                 and self.sigma_value
-                in [v for v in detection.value if type(self.sigma_value) == type(v)]
+                in [v for v in detection.value if isinstance(self.sigma_value, type(v))]
             ):
                 return True
         else:
diff --git a/sigma/processing/conditions/state.py b/sigma/processing/conditions/state.py
index ac1a89fd..41513098 100644
--- a/sigma/processing/conditions/state.py
+++ b/sigma/processing/conditions/state.py
@@ -1,6 +1,5 @@
 from dataclasses import dataclass, field
 
-import sigma
 from sigma.correlations import SigmaCorrelationRule
 from sigma.processing.conditions.base import (
     DetectionItemProcessingCondition,
diff --git a/sigma/processing/conditions/values.py b/sigma/processing/conditions/values.py
index faab08ac..81e1d281 100644
--- a/sigma/processing/conditions/values.py
+++ b/sigma/processing/conditions/values.py
@@ -1,7 +1,6 @@
 from dataclasses import dataclass
 from typing import Union
 
-import sigma
 from sigma.processing.conditions.base import (
     ValueProcessingCondition,
 )
diff --git a/sigma/processing/finalization.py b/sigma/processing/finalization.py
index 74d83985..a9d584d3 100644
--- a/sigma/processing/finalization.py
+++ b/sigma/processing/finalization.py
@@ -1,7 +1,7 @@
 from abc import abstractmethod
 from dataclasses import dataclass, field
 import json
-from typing import Any, Dict, List, Literal, Optional
+from typing import Any, Dict, List, Optional
 
 import yaml
 import sigma
@@ -107,7 +107,7 @@ def __post_init__(self):
 
     @classmethod
     def from_dict(cls, d: Dict) -> "NestedFinalizer":
-        if not "finalizers" in d:
+        if "finalizers" not in d:
             raise SigmaConfigurationError("Nested finalizer requires a 'finalizers' key.")
         fs = []
         for finalizer in d["finalizers"]:
diff --git a/sigma/processing/transformations/base.py b/sigma/processing/transformations/base.py
index adb0eebc..1de3e3dc 100644
--- a/sigma/processing/transformations/base.py
+++ b/sigma/processing/transformations/base.py
@@ -1,11 +1,8 @@
 from abc import ABC, abstractmethod
-from functools import partial
 from sigma.conditions import SigmaCondition
 from typing import (
-    Any,
     Iterable,
     List,
-    Dict,
     Optional,
     Union,
 )
@@ -58,7 +55,7 @@ def set_pipeline(self, pipeline: "sigma.processing.pipeline.ProcessingPipeline")
         if self._pipeline is None:
             self._pipeline = pipeline
         else:
-            raise SigmaTransformationError(f"Pipeline for transformation was already set.")
+            raise SigmaTransformationError("Pipeline for transformation was already set.")
 
     def _clear_pipeline(self) -> None:
         self._pipeline = None
diff --git a/sigma/processing/transformations/condition.py b/sigma/processing/transformations/condition.py
index c24f7670..b4a56918 100644
--- a/sigma/processing/transformations/condition.py
+++ b/sigma/processing/transformations/condition.py
@@ -1,7 +1,5 @@
-from abc import abstractmethod
 from sigma.conditions import SigmaCondition
 from typing import (
-    Any,
     List,
     Dict,
     Optional,
@@ -10,7 +8,6 @@
 from dataclasses import dataclass, field
 import random
 import string
-import sigma
 from sigma.processing.transformations.base import (
     ConditionTransformation,
 )
diff --git a/sigma/processing/transformations/failure.py b/sigma/processing/transformations/failure.py
index 0c23571f..d9aea533 100644
--- a/sigma/processing/transformations/failure.py
+++ b/sigma/processing/transformations/failure.py
@@ -1,5 +1,4 @@
 from dataclasses import dataclass
-import sigma
 from sigma.processing.transformations.base import (
     DetectionItemTransformation,
     Transformation,
diff --git a/sigma/processing/transformations/fields.py b/sigma/processing/transformations/fields.py
index 8d370e45..c52ac8ef 100644
--- a/sigma/processing/transformations/fields.py
+++ b/sigma/processing/transformations/fields.py
@@ -7,7 +7,6 @@
     Callable,
 )
 from dataclasses import dataclass, field
-import sigma
 from sigma.processing.transformations.base import (
     FieldMappingTransformationBase,
     Transformation,
diff --git a/sigma/processing/transformations/placeholder.py b/sigma/processing/transformations/placeholder.py
index f30027a1..a81cadf5 100644
--- a/sigma/processing/transformations/placeholder.py
+++ b/sigma/processing/transformations/placeholder.py
@@ -1,6 +1,5 @@
 from abc import abstractmethod
 from typing import (
-    Any,
     Iterable,
     List,
     Dict,
@@ -150,6 +149,6 @@ def apply_value(
                     return SigmaQueryExpression(self.expression, self.mapping.get(p.name) or p.name)
             else:  # SigmaString contains placeholder as well as other parts
                 raise SigmaValueError(
-                    f"Placeholder query expression transformation only allows placeholder-only strings."
+                    "Placeholder query expression transformation only allows placeholder-only strings."
                 )
         return None
diff --git a/sigma/processing/transformations/rule.py b/sigma/processing/transformations/rule.py
index d13e66f5..47f234a9 100644
--- a/sigma/processing/transformations/rule.py
+++ b/sigma/processing/transformations/rule.py
@@ -1,13 +1,9 @@
-from abc import abstractmethod
 from typing import (
     Any,
-    List,
-    Dict,
     Optional,
     Union,
 )
 from dataclasses import dataclass, field
-import sigma
 from sigma.correlations import SigmaCorrelationRule
 from sigma.processing.transformations.base import (
     Transformation,
diff --git a/sigma/processing/transformations/state.py b/sigma/processing/transformations/state.py
index d15ee93e..2e7b484e 100644
--- a/sigma/processing/transformations/state.py
+++ b/sigma/processing/transformations/state.py
@@ -1,6 +1,5 @@
 from typing import Any
 from dataclasses import dataclass
-import sigma
 from sigma.processing.transformations.base import Transformation
 from sigma.rule import SigmaRule
 

From 2fb79ef0ab07add5074099b114b6477580fa6f85 Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:25:29 +0100
Subject: [PATCH 6/9] fix: linting issues

---
 sigma/pipelines/test/pipeline.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sigma/pipelines/test/pipeline.py b/sigma/pipelines/test/pipeline.py
index 6d86692c..5a82bad5 100644
--- a/sigma/pipelines/test/pipeline.py
+++ b/sigma/pipelines/test/pipeline.py
@@ -4,7 +4,6 @@
 from sigma.processing.transformations import (
     AddConditionTransformation,
     FieldMappingTransformation,
-    FieldFunctionTransformation,
 )
 
 

From 61c7d72d48d5dbd6a0830f5fadc06128dfe4577e Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:37:50 +0100
Subject: [PATCH 7/9] fix: linting issues

---
 sigma/backends/test/backend.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sigma/backends/test/backend.py b/sigma/backends/test/backend.py
index 1737cb43..3feaab49 100644
--- a/sigma/backends/test/backend.py
+++ b/sigma/backends/test/backend.py
@@ -1,6 +1,6 @@
 from collections import defaultdict
 import re
-from typing import Any, ClassVar, Dict, List, Optional, Pattern, Tuple, cast
+from typing import Any, ClassVar, Dict, List, Optional, Pattern, cast
 
 from sigma.conversion.base import TextQueryBackend
 from sigma.conversion.state import ConversionState
@@ -8,7 +8,7 @@
 from sigma.processing.pipeline import ProcessingItem, ProcessingPipeline
 from sigma.processing.transformations import FieldMappingTransformation
 from sigma.rule.rule import SigmaRule
-from sigma.types import CompareOperators, SigmaCompareExpression
+from sigma.types import CompareOperators
 
 
 class TextQueryTestBackend(TextQueryBackend):

From e8cf21e43b5d3ba43539c9c273f6bc221908fade Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 19:37:54 +0100
Subject: [PATCH 8/9] fix: linting issues

---
 sigma/conversion/base.py | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/sigma/conversion/base.py b/sigma/conversion/base.py
index d2e9b1fb..42f275de 100644
--- a/sigma/conversion/base.py
+++ b/sigma/conversion/base.py
@@ -6,7 +6,6 @@
 from sigma.correlations import (
     SigmaCorrelationCondition,
     SigmaCorrelationConditionOperator,
-    SigmaCorrelationFieldAlias,
     SigmaCorrelationFieldAliases,
     SigmaCorrelationRule,
     SigmaCorrelationTimespan,
@@ -18,7 +17,6 @@
 from sigma.exceptions import (
     ExceptionOnUsage,
     SigmaBackendError,
-    SigmaConfigurationError,
     SigmaConversionError,
     SigmaError,
     SigmaValueError,
@@ -26,7 +24,6 @@
 from sigma.conversion.deferred import DeferredQueryExpression
 from typing import (
     Iterator,
-    Never,
     Pattern,
     Union,
     ClassVar,
@@ -48,7 +45,6 @@
     ConditionNOT,
     ConditionFieldEqualsValueExpression,
     ConditionValueExpression,
-    ConditionType,
 )
 from sigma.types import (
     CompareOperators,
@@ -1466,7 +1462,7 @@ def convert_condition_field_eq_val(
         def is_parent_not(
             cond: Union[
                 ConditionItem, ConditionFieldEqualsValueExpression, ConditionValueExpression
-            ]
+            ],
         ) -> bool:
             if cond.parent is None:
                 return False

From 21de9a003202706644b5c7c2d57b71cd8ce71343 Mon Sep 17 00:00:00 2001
From: Hendrik Baecker <hendrik.baecker@dcso.de>
Date: Sat, 8 Mar 2025 20:02:18 +0100
Subject: [PATCH 9/9] fix: linting issues

---
 sigma/collection.py      |  3 +--
 sigma/conditions.py      |  2 +-
 sigma/correlations.py    | 22 +++++++++++-----------
 sigma/exceptions.py      |  6 ------
 sigma/filters.py         |  1 -
 sigma/plugins.py         |  2 +-
 sigma/types.py           |  1 -
 sigma/validators/base.py |  9 ++++-----
 8 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/sigma/collection.py b/sigma/collection.py
index 9cb18799..26ba5f37 100644
--- a/sigma/collection.py
+++ b/sigma/collection.py
@@ -1,7 +1,7 @@
 from dataclasses import InitVar, dataclass, field
 from functools import reduce
 from pathlib import Path
-from typing import Any, Callable, Dict, Iterable, List, Optional, Union, IO, cast
+from typing import Any, Callable, Dict, Iterable, List, Optional, Union, IO
 from uuid import UUID
 
 import yaml
@@ -15,7 +15,6 @@
 )
 from sigma.rule import SigmaRule, SigmaRuleBase
 from sigma.filters import SigmaFilter
-from typing import TypeVar, Union
 
 NestedDict = Dict[str, Union[str, int, float, bool, None, "NestedDict"]]
 
diff --git a/sigma/conditions.py b/sigma/conditions.py
index baef315d..8bcb329a 100644
--- a/sigma/conditions.py
+++ b/sigma/conditions.py
@@ -11,7 +11,7 @@
     ParseResults,
     ParseException,
 )
-from typing import ClassVar, List, Literal, Optional, Union, Type, cast
+from typing import ClassVar, List, Optional, Union, Type, cast
 from sigma.types import SigmaType
 from sigma.exceptions import SigmaConditionError, SigmaRuleLocation
 import sigma
diff --git a/sigma/correlations.py b/sigma/correlations.py
index ffc5e322..3b22e0e7 100644
--- a/sigma/correlations.py
+++ b/sigma/correlations.py
@@ -1,6 +1,6 @@
 from dataclasses import dataclass, field
 from enum import Enum, auto
-from typing import Any, Dict, Iterator, List, Literal, Optional, Set, Union, Iterable
+from typing import Any, Dict, Iterator, List, Literal, Optional, Set, Union
 
 import sigma.exceptions as sigma_exceptions
 from sigma.exceptions import SigmaRuleLocation, SigmaTimespanError
@@ -72,7 +72,7 @@ def from_dict(
         ops = frozenset(SigmaCorrelationConditionOperator.operators())
         if len(d_keys.intersection(ops)) != 1:
             raise sigma_exceptions.SigmaCorrelationConditionError(
-                f"Sigma correlation condition must have exactly one condition item", source=source
+                "Sigma correlation condition must have exactly one condition item", source=source
             )
         unknown_keys = d_keys.difference(ops).difference({"field"})
         if unknown_keys:
@@ -268,7 +268,7 @@ def from_dict(
         else:  # no correlation type provided
             errors.append(
                 sigma_exceptions.SigmaCorrelationTypeError(
-                    f"Sigma correlation rule without type", source=source
+                    "Sigma correlation rule without type", source=source
                 )
             )
 
@@ -282,13 +282,13 @@ def from_dict(
             else:
                 errors.append(
                     sigma_exceptions.SigmaCorrelationRuleError(
-                        f"Rule reference must be plain string or list.", source=source
+                        "Rule reference must be plain string or list.", source=source
                     )
                 )
         else:
             errors.append(
                 sigma_exceptions.SigmaCorrelationRuleError(
-                    f"Sigma correlation rule without rule references", source=source
+                    "Sigma correlation rule without rule references", source=source
                 )
             )
 
@@ -298,7 +298,7 @@ def from_dict(
             if not isinstance(generate, bool):
                 errors.append(
                     sigma_exceptions.SigmaCorrelationRuleError(
-                        f"Sigma correlation generate definition must be a boolean", source=source
+                        "Sigma correlation generate definition must be a boolean", source=source
                     )
                 )
         else:
@@ -314,7 +314,7 @@ def from_dict(
             else:
                 errors.append(
                     sigma_exceptions.SigmaCorrelationRuleError(
-                        f"Sigma correlation group-by definition must be string or list",
+                        "Sigma correlation group-by definition must be string or list",
                         source=source,
                     )
                 )
@@ -329,7 +329,7 @@ def from_dict(
         else:
             errors.append(
                 sigma_exceptions.SigmaCorrelationRuleError(
-                    f"Sigma correlation rule without timespan", source=source
+                    "Sigma correlation rule without timespan", source=source
                 )
             )
 
@@ -341,7 +341,7 @@ def from_dict(
             else:
                 errors.append(
                     sigma_exceptions.SigmaCorrelationRuleError(
-                        f"Sigma correlation aliases definition must be a dict", source=source
+                        "Sigma correlation aliases definition must be a dict", source=source
                     )
                 )
         else:
@@ -355,7 +355,7 @@ def from_dict(
             else:
                 errors.append(
                     sigma_exceptions.SigmaCorrelationRuleError(
-                        f"Sigma correlation condition definition must be a dict", source=source
+                        "Sigma correlation condition definition must be a dict", source=source
                     )
                 )
         elif correlation_type not in (
@@ -364,7 +364,7 @@ def from_dict(
         ):
             errors.append(
                 sigma_exceptions.SigmaCorrelationRuleError(
-                    f"Non-temporal Sigma correlation rule without condition", source=source
+                    "Non-temporal Sigma correlation rule without condition", source=source
                 )
             )
         elif correlation_type in (
diff --git a/sigma/exceptions.py b/sigma/exceptions.py
index 2fa0b984..da87f947 100644
--- a/sigma/exceptions.py
+++ b/sigma/exceptions.py
@@ -288,12 +288,6 @@ def __str__(self):
         return f"{self.error} in expression '{self.expression}' at location {self.location}"
 
 
-class SigmaFeatureNotSupportedByBackendError(SigmaError):
-    """Sigma feature is not supported by the backend."""
-
-    pass
-
-
 class SigmaDescriptionError(SigmaError):
     """Error in Sigma rule description"""
 
diff --git a/sigma/filters.py b/sigma/filters.py
index 8e383fdc..c518af66 100644
--- a/sigma/filters.py
+++ b/sigma/filters.py
@@ -3,7 +3,6 @@
 import string
 from dataclasses import dataclass, field
 from typing import List, Optional, Union
-from uuid import UUID
 
 from sigma import exceptions as sigma_exceptions
 from sigma.correlations import SigmaCorrelationRule, SigmaRuleReference
diff --git a/sigma/plugins.py b/sigma/plugins.py
index d0d3e3fb..e260b5c0 100644
--- a/sigma/plugins.py
+++ b/sigma/plugins.py
@@ -333,7 +333,7 @@ def is_installed(self) -> bool:
         try:
             subprocess.check_call([sys.executable, "-m", "pip", "-qqq", "show", self.package])
             return True
-        except:
+        except Exception:
             return False
 
     def has_capability(self, capability: SigmaPluginCapability) -> bool:
diff --git a/sigma/types.py b/sigma/types.py
index c9bb2e8b..12cfcb8f 100644
--- a/sigma/types.py
+++ b/sigma/types.py
@@ -12,7 +12,6 @@
     Type,
     Union,
     List,
-    Tuple,
     Optional,
     Any,
     Iterable,
diff --git a/sigma/validators/base.py b/sigma/validators/base.py
index 6afabd69..2d77a389 100644
--- a/sigma/validators/base.py
+++ b/sigma/validators/base.py
@@ -1,9 +1,7 @@
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, fields
 from enum import Enum, auto
-import re
-from typing import ClassVar, Dict, List, Optional, Set, Type
-import sigma
+from typing import ClassVar, List, Optional, Set, Type
 from sigma.correlations import SigmaCorrelationRule
 from sigma.rule import SigmaDetection, SigmaDetectionItem, SigmaRule, SigmaRuleBase, SigmaRuleTag
 from sigma.types import SigmaString, SigmaType
@@ -39,12 +37,12 @@ class SigmaValidationIssue(ABC):
     severity: ClassVar[SigmaValidationIssueSeverity]
     rules: List[SigmaRuleBase]
 
-    def __post_init__(self):
+    def __post_init__(self) -> None:
         """Ensure that `self.rules` contains a list, even when a single rule was provided."""
         if isinstance(self.rules, SigmaRuleBase):
             self.rules = [self.rules]
 
-    def __str__(self):
+    def __str__(self) -> str:
         rules = ", ".join(
             [
                 str(rule.source) if rule.source is not None else str(rule.id) or rule.title
@@ -80,6 +78,7 @@ def validate(self, rule: SigmaRuleBase) -> List[SigmaValidationIssue]:
         :rtype: List[SigmaValidationIssue]
         """
         self.rule = rule
+        return []
 
     def finalize(self) -> List[SigmaValidationIssue]:
         """