Convert from numbers to letters

[Steven Bethard]

Bill Mill wrote:
>py> alpha = 'abcdefghijklmnopqrstuvwxyz'
>py> for i, digraph in enumerate(sorted([''.join((x, y)) for x in alpha
> ...    for y in [''] + [z for z in alpha]], key=len)):
> ...     locals()[digraph] = i + i
> ...

It would probably be better to get in the habit of writing
     globals()[x] = y
instead of
     locals()[x] = y
You almost never want to do the latter[1].  The only reason it works in 
this case is because, at the module level, locals() is globals().

You probably already knew this, but I note it here to help any newbies 
avoid future confusion.

Steve

[1] For 99% of use cases.  Modifying locals() might be useful if you're 
just going to pass it to another function as a dict.  But I think I've 
seen *maybe* 1 use case for this.