fact: Fixpoint nn_to_n_merge l1 l2:= if l1 is a::l then if l2 is b::s then a::b:: nn_to_n_merge l s else nn_to_n_merge1 l1 else nn_to_n_merge2 l2.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype order bigop ssralg) mathcomp(div ssrnum ssrint rat prime path binomial) mathcomp(tuple finset) gaia(fibm)