fix pep8 errors
diff --git a/cryptography/hazmat/primitives/interfaces.py b/cryptography/hazmat/primitives/interfaces.py
index 3d345a9..ba6436e 100644
--- a/cryptography/hazmat/primitives/interfaces.py
+++ b/cryptography/hazmat/primitives/interfaces.py
@@ -475,6 +475,7 @@
         The params associated with a DSA keypair
         """
 
+
 class AsymmetricSignatureContext(six.with_metaclass(abc.ABCMeta)):
     @abc.abstractmethod
     def update(self, data):