fact: Definition productions_rvalid pats := fold_right andb true (map production_rvalid pats).
imports: Coq.Strings.String Coq.Lists.List Coq.Arith.PeanoNat Fiat.Parsers.StringLike.Core Fiat.Parsers.BaseTypes Fiat.Parsers.Splitters.RDPList Fiat.Parsers.ContextFreeGrammar.Core Fiat.Parsers.ContextFreeGrammar.PreNotations Fiat.Parsers.ContextFreeGrammar.Valid