fact: Definition pack b0 (m0 : mixin_of (PCM.Pack b0)) := fun m & phant_id m0 m => Pack (@Class T b0 m).
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq bigop fintype finset) pcm(options axioms prelude seqperm pred seqext)