fact: Definition M' : TM Σ' 1 := projT1 (StateWhile (@Step Σ M) (start M)).
imports: Undecidability.TM.Compound.TMTac Undecidability.TM.Basic.Mono Undecidability.TM.Compound.Multi Undecidability.TM.Combinators.Combinators Undecidability.TM.Compound.WriteString