diff --git a/openapi_core/deserializing/parameters/deserializers.py b/openapi_core/deserializing/parameters/deserializers.py
index 7eaf6c5..5dd9135 100644
--- a/openapi_core/deserializing/parameters/deserializers.py
+++ b/openapi_core/deserializing/parameters/deserializers.py
@@ -16,7 +16,6 @@ class PrimitiveDeserializer(object):
         self.style = get_style(self.param)
 
     def __call__(self, value):
-        style = get_style(self.param)
         if (self.param['in'] == 'query' and value == "" and
                 not self.param.getkey('allowEmptyValue', False)):
             raise EmptyParameterValue(
diff --git a/openapi_core/schema/parameters.py b/openapi_core/schema/parameters.py
index f1ead22..78d39db 100644
--- a/openapi_core/schema/parameters.py
+++ b/openapi_core/schema/parameters.py
@@ -19,6 +19,6 @@ def get_explode(param):
     if 'explode' in param:
         return param['explode']
 
-    #determine default
+    # determine default
     style = get_style(param)
     return style == 'form'
diff --git a/openapi_core/templating/media_types/finders.py b/openapi_core/templating/media_types/finders.py
index 0bd3006..a677781 100644
--- a/openapi_core/templating/media_types/finders.py
+++ b/openapi_core/templating/media_types/finders.py
@@ -2,8 +2,6 @@
 from __future__ import division
 import fnmatch
 
-from six import iteritems
-
 from openapi_core.templating.media_types.exceptions import MediaTypeNotFound
 
 
diff --git a/openapi_core/templating/paths/finders.py b/openapi_core/templating/paths/finders.py
index cd7eb64..4daf6a3 100644
--- a/openapi_core/templating/paths/finders.py
+++ b/openapi_core/templating/paths/finders.py
@@ -2,7 +2,6 @@
 from __future__ import division
 
 from more_itertools import peekable
-from six import iteritems
 from six.moves.urllib.parse import urljoin, urlparse
 
 from openapi_core.schema.servers import is_absolute
diff --git a/openapi_core/unmarshalling/schemas/unmarshallers.py b/openapi_core/unmarshalling/schemas/unmarshallers.py
index e9bd6ec..9fd0789 100644
--- a/openapi_core/unmarshalling/schemas/unmarshallers.py
+++ b/openapi_core/unmarshalling/schemas/unmarshallers.py
@@ -213,7 +213,8 @@ class ObjectUnmarshaller(ComplexUnmarshaller):
         extra_props = set(value_props_names) - set(all_props_names)
 
         properties = {}
-        additional_properties = self.schema.getkey('additionalProperties', True)
+        additional_properties = self.schema.getkey(
+            'additionalProperties', True)
         if isinstance(additional_properties, dict):
             additional_prop_schema = self.schema / 'additionalProperties'
             for prop_name in extra_props:
diff --git a/openapi_core/validation/request/validators.py b/openapi_core/validation/request/validators.py
index 1414b91..fb01adf 100644
--- a/openapi_core/validation/request/validators.py
+++ b/openapi_core/validation/request/validators.py
@@ -1,7 +1,6 @@
 """OpenAPI core validation request validators module"""
 from __future__ import division
 from itertools import chain
-from six import iteritems
 
 from openapi_core.casting.schemas.exceptions import CastError
 from openapi_core.deserializing.exceptions import DeserializeError
@@ -172,7 +171,7 @@ class RequestValidator(BaseValidator):
         return RequestParameters(**locations), errors
 
     def _get_body(self, request, operation):
-        if not 'requestBody' in operation:
+        if 'requestBody' not in operation:
             return None, []
 
         request_body = operation / 'requestBody'
diff --git a/openapi_core/validation/validators.py b/openapi_core/validation/validators.py
index 51bf56c..62a70a7 100644
--- a/openapi_core/validation/validators.py
+++ b/openapi_core/validation/validators.py
@@ -39,7 +39,7 @@ class BaseValidator(object):
 
     def _cast(self, param_or_media_type, value):
         # return param_or_media_type.cast(value)
-        if not 'schema' in param_or_media_type:
+        if 'schema' not in param_or_media_type:
             return value
 
         from openapi_core.casting.schemas.factories import SchemaCastersFactory
@@ -49,13 +49,14 @@ class BaseValidator(object):
         return caster(value)
 
     def _unmarshal(self, param_or_media_type, value, context):
-        if not 'schema' in param_or_media_type:
+        if 'schema' not in param_or_media_type:
             return value
 
         from openapi_core.unmarshalling.schemas.factories import (
             SchemaUnmarshallersFactory,
         )
-        spec_resolver = self.spec.accessor.dereferencer.resolver_manager.resolver
+        spec_resolver = self.spec.accessor.dereferencer.resolver_manager.\
+            resolver
         unmarshallers_factory = SchemaUnmarshallersFactory(
             spec_resolver, self.format_checker,
             self.custom_formatters, context=context,