newbie: dictionary - howto get key value

[Joal Heagney]

Tim Roberts wrote:
> "G. Völkl" <gm.voelkl at t-online.de> wrote:
> 
>>I use a dictionary:
>>
>>phone = {'mike':10,'sue':8,'john':3}
>>
>>phone['mike']   --> 10
>>
>>I want to know who has number 3?
>>
>>3 -->  'john'
>>
>>How to get it in the python way ?
> 
> 
> If you need to do this a lot, just keep two dictionaries, where the keys in
> each are the values in the other.
> 
>   reversephone = dict( zip( phone.values(), phone.keys() ) )

(Been away from python for a while, so forgive me if I'm asking a silly 
question.)
Does python guarantee that the lists given by phone.values() and 
phone.keys() are in mutual order? Or is it possible that python will 
return the lists in different orders for .values() and .keys()?

Joal