diff --git a/apt/minimization/minimizer.py b/apt/minimization/minimizer.py
index 1d53932..9acd1b8 100644
--- a/apt/minimization/minimizer.py
+++ b/apt/minimization/minimizer.py
@@ -16,7 +16,7 @@ from sklearn.tree import DecisionTreeClassifier, DecisionTreeRegressor
 from sklearn.model_selection import train_test_split
 
 from apt.utils.datasets import ArrayDataset, DATA_PANDAS_NUMPY_TYPE
-from apt.utils.models import Model, SklearnRegressor, ModelOutputType, SklearnClassifier, \
+from apt.utils.models import Model, SklearnRegressor, SklearnClassifier, \
     CLASSIFIER_SINGLE_OUTPUT_CLASS_PROBABILITIES
 
 
diff --git a/apt/utils/models/model.py b/apt/utils/models/model.py
index 3e9ca33..8c03301 100644
--- a/apt/utils/models/model.py
+++ b/apt/utils/models/model.py
@@ -25,7 +25,7 @@ class ModelOutputType(Flag):
 CLASSIFIER_SINGLE_OUTPUT_CATEGORICAL = ModelOutputType.CLASSIFIER
 # single binary probability
 CLASSIFIER_SINGLE_OUTPUT_BINARY_PROBABILITIES = ModelOutputType.CLASSIFIER | ModelOutputType.BINARY | \
-                                                ModelOutputType.PROBABILITIES
+    ModelOutputType.PROBABILITIES
 # vector of class probabilities
 CLASSIFIER_SINGLE_OUTPUT_CLASS_PROBABILITIES = ModelOutputType.CLASSIFIER | ModelOutputType.PROBABILITIES
 # single binary logit
@@ -36,16 +36,16 @@ CLASSIFIER_SINGLE_OUTPUT_CLASS_LOGITS = ModelOutputType.CLASSIFIER | ModelOutput
 CLASSIFIER_MULTI_OUTPUT_CATEGORICAL = ModelOutputType.MULTI_OUTPUT | ModelOutputType.CLASSIFIER
 # vector of binary probabilities, 1 per output
 CLASSIFIER_MULTI_OUTPUT_BINARY_PROBABILITIES = ModelOutputType.MULTI_OUTPUT | ModelOutputType.CLASSIFIER | \
-                                               ModelOutputType.BINARY | ModelOutputType.PROBABILITIES
+    ModelOutputType.BINARY | ModelOutputType.PROBABILITIES
 # vector of class probabilities for multiple outputs
 CLASSIFIER_MULTI_OUTPUT_CLASS_PROBABILITIES = ModelOutputType.MULTI_OUTPUT | ModelOutputType.CLASSIFIER | \
-                                              ModelOutputType.PROBABILITIES
+    ModelOutputType.PROBABILITIES
 # vector of binary logits
 CLASSIFIER_MULTI_OUTPUT_BINARY_LOGITS = ModelOutputType.MULTI_OUTPUT | ModelOutputType.CLASSIFIER | \
-                                        ModelOutputType.BINARY | ModelOutputType.LOGITS
+    ModelOutputType.BINARY | ModelOutputType.LOGITS
 # vector of logits for multiple outputs
 CLASSIFIER_MULTI_OUTPUT_CLASS_LOGITS = ModelOutputType.MULTI_OUTPUT | ModelOutputType.CLASSIFIER | \
-                                       ModelOutputType.LOGITS
+    ModelOutputType.LOGITS
 
 
 class ModelType(Enum):
@@ -79,9 +79,9 @@ def is_binary(output_type: ModelOutputType) -> bool:
 
 def is_categorical(output_type: ModelOutputType) -> bool:
     return (ModelOutputType.CLASSIFIER in output_type
-            and not ModelOutputType.BINARY in output_type
-            and not ModelOutputType.PROBABILITIES in output_type
-            and not ModelOutputType.LOGITS in output_type)
+            and ModelOutputType.BINARY not in output_type
+            and ModelOutputType.PROBABILITIES not in output_type
+            and ModelOutputType.LOGITS not in output_type)
 
 
 def is_probabilities(output_type: ModelOutputType) -> bool:
diff --git a/tests/test_model.py b/tests/test_model.py
index 0667b7a..dbfadb2 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -3,11 +3,9 @@ import numpy as np
 
 from apt.utils.models import SklearnClassifier, SklearnRegressor, ModelOutputType, KerasClassifier, KerasRegressor, \
     BlackboxClassifierPredictions, BlackboxClassifierPredictFunction, is_one_hot, get_nb_classes, XGBoostClassifier, \
-    CLASSIFIER_SINGLE_OUTPUT_CATEGORICAL, CLASSIFIER_SINGLE_OUTPUT_BINARY_PROBABILITIES, \
-    CLASSIFIER_SINGLE_OUTPUT_CLASS_PROBABILITIES, CLASSIFIER_SINGLE_OUTPUT_BINARY_LOGITS, \
-    CLASSIFIER_SINGLE_OUTPUT_CLASS_LOGITS, CLASSIFIER_MULTI_OUTPUT_CATEGORICAL, \
-    CLASSIFIER_MULTI_OUTPUT_BINARY_PROBABILITIES, CLASSIFIER_MULTI_OUTPUT_CLASS_PROBABILITIES, \
-    CLASSIFIER_MULTI_OUTPUT_BINARY_LOGITS, CLASSIFIER_MULTI_OUTPUT_CLASS_LOGITS
+    CLASSIFIER_SINGLE_OUTPUT_CATEGORICAL, CLASSIFIER_SINGLE_OUTPUT_CLASS_PROBABILITIES, \
+    CLASSIFIER_MULTI_OUTPUT_CATEGORICAL, CLASSIFIER_MULTI_OUTPUT_BINARY_PROBABILITIES, \
+    CLASSIFIER_MULTI_OUTPUT_CLASS_PROBABILITIES
 from apt.utils.datasets import ArrayDataset, Data, DatasetWithPredictions
 from apt.utils import dataset_utils