let pnv,piv= (fun expr -> string_of_lambda (cbv expr)), (fun expr -> to_int (cbv expr))
let db, db_equal, db_contains = db, db_equal, db_contains
let pnv,piv= (fun expr -> string_of_lambda (cbv expr)), (fun expr -> to_int (cbv expr))
let db, db_equal, db_contains = db, db_equal, db_contains