Are there any existing python libs/classes that allow for key value pair retrieval by case insensitive partial key match?

blah = { 'aaa':3, 'aab':5, 'bbb':4 }

blah.get('A') => [('aaa',3),('aab',5)]

EDIT

ah so the best way to describe this is, code-completion.

what libraries or packages or data structues can i leverage to implement code-completion in my app

i really like the common infrastructure that eclipse leverages for this