PEP8: Code cleanups

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/common/compressed_files.py

@@ -83,7 +83,7 @@ class Archive(object):
         """
         Return a file-like object to a member of the archive
         """
-        raise NotImplemented
+        raise NotImplementedError
 
 
 class TarArchive(Archive):

mayan/apps/smart_settings/apps.py

@@ -2,9 +2,7 @@ from __future__ import unicode_literals
 
 from django.utils.translation import ugettext_lazy as _
 
-from common import (
-    MayanAppConfig, menu_facet, menu_sidebar, menu_setup, menu_object
-)
+from common import MayanAppConfig, menu_facet, menu_setup, menu_object
 from navigation import SourceColumn
 
 from .classes import Namespace, Setting

mayan/apps/smart_settings/forms.py

@@ -20,8 +20,6 @@ class SettingForm(forms.Form):
         self.fields['value'].initial = self.setting.serialized_value
 
     def clean(self):
-        quotes = ['"', "'"]
-
         try:
             yaml.safe_load(self.cleaned_data['value'])
         except yaml.YAMLError: