1 files changed, 9 insertions, 7 deletions
diff --git a/sphinx/transforms/references.py b/sphinx/transforms/references.py
index 2d66b44f6..fd7e71779 100644
--- a/sphinx/transforms/references.py
+++ b/sphinx/transforms/references.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 """
     sphinx.transforms.references
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -11,10 +10,13 @@
 
 from docutils import nodes
 from docutils.transforms.references import Substitutions
-from six import itervalues
 
 from sphinx.transforms import SphinxTransform
 
+if False:
+    # For type annotation
+    from typing import Any  # NOQA
+
 
 class SubstitutionDefinitionsRemover(SphinxTransform):
     """Remove ``substitution_definition node from doctrees."""
@@ -22,8 +24,8 @@ class SubstitutionDefinitionsRemover(SphinxTransform):
     # should be invoked after Substitutions process
     default_priority = Substitutions.default_priority + 1
 
-    def apply(self):
-        # type: () -> None
+    def apply(self, **kwargs):
+        # type: (Any) -> None
         for node in self.document.traverse(nodes.substitution_definition):
             node.parent.remove(node)
 
@@ -32,7 +34,7 @@ class SphinxDomains(SphinxTransform):
     """Collect objects to Sphinx domains for cross references."""
     default_priority = 850
 
-    def apply(self):
-        # type: () -> None
-        for domain in itervalues(self.env.domains):
+    def apply(self, **kwargs):
+        # type: (Any) -> None
+        for domain in self.env.domains.values():
             domain.process_doc(self.env, self.env.docname, self.document)