decipher-loop-with-breaks is a compiled Lisp function in `
Loop through ciphertext, calling FUNC once for each letter & word division.
FUNC is called with no arguments, and its return value is unimportant.
It may examine `decipher-char' to see the current ciphertext
character. `decipher-char' contains either an uppercase letter or a space.
FUNC is called exactly once between words, with `decipher-char' set to
See `decipher-loop-no-breaks' if you do not care about word divisions.