Add missing typing to Extension

UM/Extension.py

@@ -1,9 +1,9 @@
-# Copyright (c) 2015 Ultimaker B.V.
+# Copyright (c) 2020 Ultimaker B.V.
 # Uranium is released under the terms of the LGPLv3 or higher.
 
 from UM.PluginObject import PluginObject
 import collections
-from typing import Optional, Any, Callable, List
+from typing import Optional, Any, Callable, List, Dict
 
 
 class Extension(PluginObject):
@@ -13,21 +13,21 @@ class Extension(PluginObject):
     more menu items.
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         super().__init__()
-        self._menu_function_dict = collections.OrderedDict()
+        self._menu_function_dict = collections.OrderedDict()  # type: Dict[str, Callable[[], Any]]
         self._menu_name = None  # type: Optional[str]
 
-    def addMenuItem(self, name: str, func: Callable[[], Any]):
+    def addMenuItem(self, name: str, function: Callable[[], Any]) -> None:
         """Add an item to the sub-menu of the extension
 
         :param name: :type{string}
         :param function: :type{function}
         """
 
-        self._menu_function_dict[name] = func
+        self._menu_function_dict[name] = function
 
-    def setMenuName(self, name: str):
+    def setMenuName(self, name: str) -> None:
         """Set name of the menu where all menu items are placed in
 
         :param name: :type{string}
@@ -40,7 +40,7 @@ def getMenuName(self) -> Optional[str]:
 
         return self._menu_name
 
-    def activateMenuItem(self, name: str):
+    def activateMenuItem(self, name: str) -> None:
         """Call function associated with option
 
         :param name: :type{string}