Add some missing type documentation and remove an unused import.
diff --git a/OpenSSL/test/test_ssl.py b/OpenSSL/test/test_ssl.py
index a2dfb8a..c82dea6 100644
--- a/OpenSSL/test/test_ssl.py
+++ b/OpenSSL/test/test_ssl.py
@@ -14,7 +14,7 @@
 from unittest import main
 from weakref import ref
 
-from six import PY3, binary_type, text_type, u
+from six import PY3, text_type, u
 
 from OpenSSL.crypto import TYPE_RSA, FILETYPE_PEM
 from OpenSSL.crypto import PKey, X509, X509Extension, X509Store
@@ -1375,6 +1375,10 @@
 
 
     def _load_tmp_dh_test(self, dhfilename):
+        """
+        Verify that calling ``Context.load_tmp_dh`` with the given filename
+        does not raise an exception.
+        """
         context = Context(TLSv1_METHOD)
         with open(dhfilename, "w") as dhfile:
             dhfile.write(dhparam)