rewrite-indented

(require '[rewrite-indented.zip :as z])
;; => nil

(-> (z/of-string "foo\n  TARGET\n    bar")
    (z/find-next-string #(= "TARGET" %))
    (z/update (constantly "hello"))
    (z/root-string))
;; => "foo\n  hello\n    bar"

(loop [zloc (z/of-string "first\n  TARGET\n    foo\nsecond\n  TARGET\n    bar")]
  (if-let [zloc (z/find-next-string zloc #(= "TARGET" %))]
    (recur
     (cond-> zloc
       (z/find-ancestor-string zloc #(= "second" %))
       (z/update (constantly "hello"))

       :always
       (z/next)))
    (z/root-string zloc)))
;; => "first\n  TARGET\n    foo\nsecond\n  hello\n    bar"