protocolsince v1.11.121Edit
implemented for ChunkedSeq IndexedSeq IntegerRange PersistentArrayMap PersistentArrayMapSeq PersistentVector Repeat

Source docstring:
Protocol for persistent or algorithmically defined collections to provide a
  means of dropping N items that is more efficient than sequential walking.
Source code @ clojurescript:src/main/cljs/cljs/core.cljs
(defprotocol IDrop
  (^clj-or-nil -drop [coll n]
    "Returns a collection that is ISequential, ISeq, and IReduce, or nil if past
     the end. The number of items to drop n must be > 0. It is also useful if the
     returned coll implements IDrop for subsequent use in a partition-like scenario."))