I'd like to point out that the strange occurrences of the "=3D" string are due to the fact that the message was originally a "quoted-printable" encoded email and for whatever reason this artifact wasn't removed when posted to the web. Perhaps this was pipermail's fault?
Anyway, when reading the code, you're safe in assuming "=3D" is just a single plain old equal sign. In the "quoted-printable" encoding scheme the two characters following an equal sign are the hex value of the intended character. In effect, equal signs need to be escaped using the "=3D" sequence.
This drove me a little nuts as I was reading and trying to code switch between the assorted languages used in the examples.
Quite sad btw that many lisp book are old. And wonder if those Perl book can they be rewritten at least just GitHub source code only for study purpose.
Anyway, when reading the code, you're safe in assuming "=3D" is just a single plain old equal sign. In the "quoted-printable" encoding scheme the two characters following an equal sign are the hex value of the intended character. In effect, equal signs need to be escaped using the "=3D" sequence.
This drove me a little nuts as I was reading and trying to code switch between the assorted languages used in the examples.