diff --git a/stix2/STIXPatternVisitor.py b/stix2/STIXPatternVisitor.py
index 43be107..89b79da 100644
--- a/stix2/STIXPatternVisitor.py
+++ b/stix2/STIXPatternVisitor.py
@@ -3,20 +3,20 @@ import inspect
 
 import six
 from stix2patterns.grammars.STIXPatternLexer import STIXPatternLexer
-from stix2patterns.grammars.STIXPatternParser import (
-    STIXPatternParser, TerminalNode,
-)
+from stix2patterns.grammars.STIXPatternParser import (STIXPatternParser,
+                                                      TerminalNode)
 from stix2patterns.grammars.STIXPatternVisitor import STIXPatternVisitor
 from stix2patterns.validator import STIXPatternErrorListener
-from stix2.patterns import _BooleanExpression
 
 from antlr4 import CommonTokenStream, InputStream
+from stix2.patterns import _BooleanExpression
 
 # need to import all classes because we need to access them via globals()
+from .patterns import (BinaryConstant, BooleanConstant, FloatConstant,
+                       FollowedByObservationExpression, HexConstant,
+                       IntegerConstant, RepeatQualifier, StartStopQualifier,
+                       StringConstant, TimestampConstant, WithinQualifier)
 from .patterns import *  # noqa
-from .patterns import (FollowedByObservationExpression, StartStopQualifier, WithinQualifier,
-                       RepeatQualifier, StringConstant, IntegerConstant, FloatConstant, HexConstant,
-                       BinaryConstant, BooleanConstant, TimestampConstant)
 
 
 def collapse_lists(lists):
diff --git a/stix2/__init__.py b/stix2/__init__.py
index 3d70001..449be68 100644
--- a/stix2/__init__.py
+++ b/stix2/__init__.py
@@ -54,7 +54,6 @@ from .utils import new_version, revoke
 from .v20 import *  # This import will always be the latest STIX 2.X version
 from .version import __version__
 
-
 _collect_stix2_obj_maps()
 
 DEFAULT_VERSION = "2.0"  # Default version will always be the latest STIX 2.X version
diff --git a/stix2/patterns.py b/stix2/patterns.py
index fec060e..1e0e03f 100644
--- a/stix2/patterns.py
+++ b/stix2/patterns.py
@@ -5,6 +5,7 @@ import base64
 import binascii
 import datetime
 import re
+
 import six
 
 from .utils import parse_into_datetime
diff --git a/stix2/test/test_pattern_expressions.py b/stix2/test/test_pattern_expressions.py
index c136eaa..0aff872 100644
--- a/stix2/test/test_pattern_expressions.py
+++ b/stix2/test/test_pattern_expressions.py
@@ -3,7 +3,6 @@ import datetime
 import pytest
 
 import stix2
-
 from stix2.STIXPatternVisitor import create_pattern_object