(** Completeness part 2: if we can reduce to [Stuckstate], [step_expr] contains at least one [Stuckred] reduction. *)

Lemma not_imm_safe_stuck_red:
forall m a k C,
context k RV C ->
~imm_safe_t k a m ->
exists C', In (C', Stuckred) (step_expr RV (C a) m).