diff --git a/stix2/__init__.py b/stix2/__init__.py
index 9047862..3bedec8 100644
--- a/stix2/__init__.py
+++ b/stix2/__init__.py
@@ -32,40 +32,32 @@ from .confidence import scales
 from .core import _collect_stix2_mappings, parse, parse_observable
 from .datastore import CompositeDataSource
 from .datastore.filesystem import (
-    FileSystemSink, FileSystemSource,
-    FileSystemStore
+    FileSystemSink, FileSystemSource, FileSystemStore,
 )
 from .datastore.filters import Filter
 from .datastore.memory import MemorySink, MemorySource, MemoryStore
 from .datastore.taxii import (
-    TAXIICollectionSink, TAXIICollectionSource,
-    TAXIICollectionStore
+    TAXIICollectionSink, TAXIICollectionSource, TAXIICollectionStore,
 )
 from .environment import Environment, ObjectFactory
 from .markings import (
-    add_markings, clear_markings, get_markings, is_marked,
-    remove_markings, set_markings
+    add_markings, clear_markings, get_markings, is_marked, remove_markings,
+    set_markings,
 )
 from .patterns import (
-    AndBooleanExpression, AndObservationExpression,
-    BasicObjectPathComponent, BinaryConstant,
-    BooleanConstant, EqualityComparisonExpression,
+    AndBooleanExpression, AndObservationExpression, BasicObjectPathComponent,
+    BinaryConstant, BooleanConstant, EqualityComparisonExpression,
     FloatConstant, FollowedByObservationExpression,
-    GreaterThanComparisonExpression,
-    GreaterThanEqualComparisonExpression, HashConstant,
-    HexConstant, InComparisonExpression, IntegerConstant,
-    IsSubsetComparisonExpression,
-    IsSupersetComparisonExpression,
-    LessThanComparisonExpression,
-    LessThanEqualComparisonExpression,
-    LikeComparisonExpression, ListConstant,
-    ListObjectPathComponent, MatchesComparisonExpression,
-    ObjectPath, ObservationExpression, OrBooleanExpression,
-    OrObservationExpression, ParentheticalExpression,
-    QualifiedObservationExpression,
-    ReferenceObjectPathComponent, RepeatQualifier,
-    StartStopQualifier, StringConstant, TimestampConstant,
-    WithinQualifier
+    GreaterThanComparisonExpression, GreaterThanEqualComparisonExpression,
+    HashConstant, HexConstant, InComparisonExpression, IntegerConstant,
+    IsSubsetComparisonExpression, IsSupersetComparisonExpression,
+    LessThanComparisonExpression, LessThanEqualComparisonExpression,
+    LikeComparisonExpression, ListConstant, ListObjectPathComponent,
+    MatchesComparisonExpression, ObjectPath, ObservationExpression,
+    OrBooleanExpression, OrObservationExpression, ParentheticalExpression,
+    QualifiedObservationExpression, ReferenceObjectPathComponent,
+    RepeatQualifier, StartStopQualifier, StringConstant, TimestampConstant,
+    WithinQualifier,
 )
 from .utils import new_version, revoke
 from .v20 import *  # This import will always be the latest STIX 2.X version
diff --git a/stix2/test/v20/test_custom.py b/stix2/test/v20/test_custom.py
index 2ecf16f..40ffa88 100644
--- a/stix2/test/v20/test_custom.py
+++ b/stix2/test/v20/test_custom.py
@@ -884,9 +884,10 @@ def test_parse_observable_with_custom_extension():
     assert parsed.extensions['x-new-ext'].property2 == 12
 
 
-@pytest.mark.parametrize("data", [
-    # URL is not in EXT_MAP
-    """{
+@pytest.mark.parametrize(
+    "data", [
+        # URL is not in EXT_MAP
+        """{
         "type": "url",
         "value": "example.com",
         "extensions": {
@@ -896,8 +897,8 @@ def test_parse_observable_with_custom_extension():
             }
         }
     }""",
-    # File is in EXT_MAP
-    """{
+        # File is in EXT_MAP
+        """{
         "type": "file",
         "name": "foo.txt",
         "extensions": {
@@ -907,7 +908,8 @@ def test_parse_observable_with_custom_extension():
             }
         }
     }""",
-])
+    ],
+)
 def test_parse_observable_with_unregistered_custom_extension(data):
     with pytest.raises(ValueError) as excinfo:
         stix2.parse_observable(data, version='2.0')
diff --git a/stix2/test/v20/test_datastore_memory.py b/stix2/test/v20/test_datastore_memory.py
index 8f2a446..279026c 100644
--- a/stix2/test/v20/test_datastore_memory.py
+++ b/stix2/test/v20/test_datastore_memory.py
@@ -289,7 +289,7 @@ def test_memory_store_object_creator_of_present(mem_store):
     iden = Identity(
         id="identity--e4196283-7420-4277-a7a3-d57f61ef1389",
         name="Foo Corp.",
-        identity_class="corporation"
+        identity_class="corporation",
     )
 
     mem_store.add(camp)
diff --git a/stix2/test/v21/test_custom.py b/stix2/test/v21/test_custom.py
index 0e897bc..295520e 100644
--- a/stix2/test/v21/test_custom.py
+++ b/stix2/test/v21/test_custom.py
@@ -888,9 +888,10 @@ def test_parse_observable_with_custom_extension():
     assert parsed.extensions['x-new-ext'].property2 == 12
 
 
-@pytest.mark.parametrize("data", [
-    # URL is not in EXT_MAP
-    """{
+@pytest.mark.parametrize(
+    "data", [
+        # URL is not in EXT_MAP
+        """{
         "type": "url",
         "value": "example.com",
         "extensions": {
@@ -900,8 +901,8 @@ def test_parse_observable_with_custom_extension():
             }
         }
     }""",
-    # File is in EXT_MAP
-    """{
+        # File is in EXT_MAP
+        """{
         "type": "file",
         "name": "foo.txt",
         "extensions": {
@@ -911,7 +912,8 @@ def test_parse_observable_with_custom_extension():
             }
         }
     }""",
-])
+    ],
+)
 def test_parse_observable_with_unregistered_custom_extension(data):
     with pytest.raises(ValueError) as excinfo:
         stix2.parse_observable(data, version='2.1')
diff --git a/stix2/test/v21/test_datastore_memory.py b/stix2/test/v21/test_datastore_memory.py
index 4fc276b..3a76fbc 100644
--- a/stix2/test/v21/test_datastore_memory.py
+++ b/stix2/test/v21/test_datastore_memory.py
@@ -10,7 +10,7 @@ from stix2.v21 import (
     Bundle, Campaign, CustomObject, Identity, Indicator, Malware, Relationship,
 )
 
-from stix2.test.v21.constants import (
+from .constants import (
     CAMPAIGN_ID, CAMPAIGN_KWARGS, IDENTITY_ID, IDENTITY_KWARGS, INDICATOR_ID,
     INDICATOR_KWARGS, MALWARE_ID, MALWARE_KWARGS, RELATIONSHIP_IDS,
 )
@@ -296,7 +296,7 @@ def test_memory_store_object_creator_of_present(mem_store):
     iden = Identity(
         id="identity--e4196283-7420-4277-a7a3-d57f61ef1389",
         name="Foo Corp.",
-        identity_class="corporation"
+        identity_class="corporation",
     )
 
     mem_store.add(camp)