`fxmapping-split``fxmap``k`procedureReturns two fxmappings. The first contains all of the associations of

*fxmap*whose keys are less than or equal to*k*, and the second contains the remaining associations. This is equivalent to(values (fxsubmapping<= fxmap k) (fxsubmapping> fxmap k))

but is implemented more efficiently.

If

*fxmap*is empty, then both of the fxmappings returned by`fxmapping-split`are empty.Example:

(let-values ((fxmaps (fxmapping-split (fxmapping 0 'a 1 'b 2 'c 3 'd) 2))) (map fxmapping->alist fxmaps)) ⇒ (((0 . a) (1 . b) (2 . c)) ((3 . d)))