Update base.py (#750)

Lib/fontParts/base/base.py

@@ -830,8 +830,14 @@ def _setIdentifier(self, value):
 
 
 def reference(obj):
-    # import weakref
-    # return weakref.ref(obj)
+    """
+    This code returns a simple function that returns the given object.
+    This is a backwards compatibility function that is under review. 
+    See #749. We used to use weak references, but they proved 
+    problematic (see issue #71), so this function was put in place to 
+    make sure existing code continued to function. The need for it is 
+    questionable, so it may be deleted soon.
+    """
     def wrapper():
         return obj
     return wrapper