(flatten ..its)
  its: zero or more iterables
  returns an iter
F

Flattens nested structure.

Each iterable in its must be an iterable which, when iterated, produces zero or more iterables. For example, (flatten '((0 1) (2 3))) would be valid, because the argument is an array of arrays.

(prn ..(flatten '((0 1) (2 3)))) ; prints 0 1 2 3
chain
cycle