(find f it)
  f: a callable
  it: an iterable
  returns any type
F

Returns the first of an iterator's items which match a predicate.

Repeatedly produces items from the base iterator and passes them to (f item). If that call returns anything other than #n or #f, the function exits early and returns the item. If the iterator is finished before that occurs, the function returns #n.

all?
rfind