diff --git a/Lib/enum.py b/Lib/enum.py
index ed0c9ce..0070ebe 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -136,7 +136,7 @@ def __setitem__(self, key, value):
                 key = '_order_'
         elif key in self._member_names:
             # descriptor overwriting an enum?
-            raise TypeError('Attempted to reuse key: %r' % key)
+            raise TypeError('%r already defined as: %r' % (key, self[key]))
         elif key in self._ignore:
             pass
         elif not _is_descriptor(value):
@@ -157,6 +157,16 @@ def __setitem__(self, key, value):
             self._last_values.append(value)
         super().__setitem__(key, value)
 
+    def update(self, members, **more_members):
+        try:
+            for name in members.keys():
+                self[name] = members[name]
+        except AttributeError:
+            for name, value in members:
+                self[name] = value
+        for name, value in more_members.items():
+            self[name] = value
+
 
 # Dummy value for Enum as EnumMeta explicitly checks for it, but of course
 # until EnumMeta finishes running the first time the Enum class doesn't exist.