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(* modify it under the terms of the GNU Lesser General Public License *)
(* as published by the Free Software Foundation; either version 2.1   *)
(* of the License, or (at your option) any later version.             *)
(*                                                                    *)
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(* but WITHOUT ANY WARRANTY; without even the implied warranty of     *)
(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the      *)
(* GNU General Public License for more details.                       *)
(*                                                                    *)
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(* 02110-1301 USA                                                     *)

Lemma bool_fun_or_preserves_eq :
forall bf1 bf2 bf1' bf2' : bool_fun,
bool_fun_eq bf1 bf1' ->
bool_fun_eq bf2 bf2' ->
bool_fun_eq (bool_fun_or bf1 bf2) (bool_fun_or bf1' bf2').