--- a/taskcluster/actions/__init__.py
+++ b/taskcluster/actions/__init__.py
@@ -1,9 +1,17 @@
-from registry import (
+# -*- coding: utf-8 -*-
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+from .registry import (
     register_task_action, register_callback_action, render_actions_json, trigger_action_callback,
 )
 
 __all__ = [
     'register_task_action',
     'register_callback_action',
     'render_actions_json',
     'trigger_action_callback',

--- a/taskcluster/actions/hello-action.py
+++ b/taskcluster/actions/hello-action.py
@@ -1,8 +1,16 @@
+# -*- coding: utf-8 -*-
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
 from .registry import register_callback_action
 
 
 @register_callback_action(
     name='hello',
     title='Say Hello',
     symbol='hw',
     description="""
@@ -20,12 +28,12 @@ from .registry import register_callback_
 A name wish to say hello to...
 This should normally be **your name**.
 
 But you can also use the default value `'World'`.
         """.strip(),
     },
 )
 def hello_world_action(parameters, input, task_group_id, task_id, task):
-    print "This message was triggered from context-menu of taskId: {}".format(task_id)
-    print ""
-    print "Hello {}".format(input)
-    print "--- Action is now executed"
+    print("This message was triggered from context-menu of taskId: {}".format(task_id))
+    print("")
+    print("Hello {}".format(input))
+    print("--- Action is now executed")

--- a/taskcluster/actions/registry.py
+++ b/taskcluster/actions/registry.py
@@ -1,8 +1,16 @@
+# -*- coding: utf-8 -*-
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
 import json
 import os
 import inspect
 import re
 from types import FunctionType
 from collections import namedtuple
 from taskgraph.util.docker import docker_image
 from taskgraph.parameters import Parameters