(let [m {a 1 b 2} changed (remove (collections/copy .m) a)] [.m .changed])
(let [m {a {b 1 c 2}} changed (remove (collections/copy .m) (jsonptr "/a/b"))] [.m .changed])
(let
  [m {a {b 1 c 2}} changed (remove (collections/copy .m shallow) (jsonptr "/a/b"))]
  [.m .changed])
(let [xs [Ada Bea] changed (remove (collections/copy .xs) 0)] [.xs .changed])