proposition: Lemma mem_range k v f : (k, v) \In f -> v \in range f.
proof: Proof. by move/In_range/mem_seqP. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)