__ABOUT__ 
Decoder Ring program, written to solve the secret messages in Joe
Meno's novel "The Boy Detective Fails" (I didn't want to cut up the
cover of the book).

__USAGE__ 
$ python decoder_ring.py <input_file>

Input file should have two lines: 1: letter and number to align on the
inner and outer discs of the decoder ring. These should be separated
by a space.  2: message to decode. In the novel, letters are separated
by a dash.