best way to determine sequence ordering?

[John Salerno]

If I want to make a list of four items, e.g. L = ['C', 'A', 'D', 'B'], 
and then figure out if a certain element precedes another element, what 
would be the best way to do that?

Looking at the built-in list functions, I thought I could do something like:

if L.index('A') < L.index('D'):
     # do some stuff

But I didn't know if maybe there was a preferred method for this type of 
operation, or perhaps a better function to use to figure out the 
ordering. Or even if I wanted to write my own utility function to make 
it look cleaner than above, I'd still need to use something like above 
in my function, so I wanted to know what might be the 'cleanest' looking 
solution.

Thanks.