BIO_f_prefix
b = BIO_push(BIO_new(BIO_f_prefix()), b);
BIO *bio, *pre = BIO_new(BIO_f_prefix());
bio = BIO_new(BIO_f_prefix());
if ((bio = BIO_new(BIO_f_prefix())) == NULL
BIO *prefbio = BIO_new(BIO_f_prefix());
const BIO_METHOD *BIO_f_prefix(void);
BIO *curr = BIO_new(BIO_f_prefix());
tap_out = BIO_push(BIO_new(BIO_f_prefix()), tap_out);
tap_err = BIO_push(BIO_new(BIO_f_prefix()), tap_err);
bio_out = BIO_push(BIO_new(BIO_f_prefix()), tap_out);
bio_err = BIO_push(BIO_new(BIO_f_prefix()), tap_err);
bio = BIO_new(BIO_f_prefix());