protocolsince v0.0-927 clojure.lang/ILookupEdit
implemented for BlackNode MapEntry ObjMap PersistentArrayMap PersistentHashMap PersistentHashSet PersistentTreeMap PersistentTreeSet PersistentVector RedNode Subvec TaggedLiteral TransientArrayMap TransientHashMap TransientHashSet TransientVector

Source docstring:
Protocol for looking up a value in a data structure.
Source code @ clojurescript:src/main/cljs/cljs/core.cljs
(defprotocol ILookup
  (-lookup [o k] [o k not-found]
    "Use k to look up a value in o. If not-found is supplied and k is not
     a valid value that can be used for look up, not-found is returned."))