(** Commutation with [find_label]. *)

Corollary find_label_translated:
forall f i c' lbl c,
incl (i :: c') (fn_code f) ->
find_label lbl (fn_code f) = Some c ->
instr_branches_to i lbl ->
find_label lbl (fn_code (transf_function f)) =
Some (remove_unused_labels (labels_branched_to (fn_code f)) c).