(= (length elt) 4)
(= (aref elt 1) ?:)))
[0 1] [2 4] ,#'(lambda () 0))
+ ((2 1 0)
+ ,#'(lambda () (and (stringp elt)
+ (= (length elt) 7)
+ (= (aref elt 1) ?:)))
+ [0 1] [2 4] [5 7])
((5) (70 99) ,#'(lambda () (+ 1900 elt))))
"(slots predicate extractor...)")