pin*; ranges are
[!sz] (!!). Character classes:
@ = [aeiou],
# = consonant including y.
> = word,
< = reversed word, so e.g.
s> are S prefix hooks.
7-9:x*a = length constraint (either bound can be omitted);
&|! intersect, union, or set-subtract constraints.
A-Z mean strings, constraints separated by
; force them to be words, e.g. cyclically permuted words are
AB;BA, words that take a K to L misprint are
~A is reversed A. Different constraints:
!=A<B<C. Length constraints:
|A|=3-7. Note that string variables are nonempty by default; add
|A|=0- to override.