code: func (rev *Revocation) Insert(tx *sql.Tx) error {
  	_, err := tx.Exec(`INSERT INTO revocations (ski, revoked_at, mechanism, reason) VALUES (?, ?, ?, ?)`, rev.SKI, rev.RevokedAt, rev.Mechanism, rev.Reason)
  	return err
  }
docs: // Insert adds the revocation to the database if no revocation exists
  // yet.