Is there such a thing as an ordered dict?

[VanL]

I am trying to implement an outline as a tree of nodes.  This would seem 
to be most easily accomplished using a dict, where the name of the node 
was the key, and the value of the node the hash (including any subnodes).

Unfortunately, the outline needs to also be order-aware -- that is, I 
can't have a user enter an outline like this

I Head 1
   A. Subhead 1 (content)
   B. Subhead 2 (content)
II. Head 2 (content)
III. Head 3

and have it be printed as

II. Head 2 (content)
III Head 3
I Head 1
   B. Subhead 2 (content)
   A. Subhead 1 (content)

 Is there some sort of halfway-dict halfway-list that could be accessed 
 by key *and* by position?  So that the following would work:

[ Assume half-and-half structure as described above, with the outline 
above entered in an instance called OUTLINE]

 >>> 'Head 2' in OUTLINE
1
 >>>  OUTLINE['Head 2']
'(content)'
 >>> for x in OUTLINE: print x, OUTLINE[x]
'Head 1'  ['Subhead 1', 'Subhead 2']
'Head 2'
'Head 3'  '(content)'
 >>> for x in range(len(OUTLINE)): print x, OUTLINE[x]
0  'Head 1'
1  'Head 2'
2  'Head 3'

TIA