fact: Definition texists {A} {Q:A->Prop} : ttac (exists (x:A), Q x) := e <- M.evar A; pf <- M.evar (Q e); M.ret (m: ex_intro _ e pf, [m: AnyMetavar Propₛ _ pf]).
imports: Mtac2(Base Datatypes List Sorts tactics.Tactics) Strings.String