[Tutor] Dictionary questions

[Isaac Hall]

Hi everyone, I usually read this mailing list multiple times every day, but I
havent been able to do so for the last week or so, due to a rather heavy
workload.  anyway, in the work Im doing, it turns out I need to take a number
that gets spit out of something, and using the information from several
functions that could have created that number determine a) what function was
used, and b) what its parameters were, knowing that they came from a particular
set of numbers (some of them in a dictonary).   so anyway, with that setup,
here is my question:

supposing I can determine all of this, is there a way to get the key back out
of a dictonary simply by asking for the content.  

if not:
    is there a better structure to use which will make correlation between key
    and content (in this case, there will only be one to one mapping) by which
    I can get one by knowing the other and vice versa

if anyone can help, I would surely appreciate it
Thanks, 
Ike