(enumerate it)
  it: an iterable
  returns an iter
F

Counts an iterator's items as they're yielded.

Returns an iterator which produces mutable arrays with two elements, (n item), where n counts upwards starting from 0, and item is the result of calling (iter-next! it).

(prn ..(enumerate '(x y))) ; prints (0 x) (1 y)
rev
cloned