code: func (c *Config) SetSessionTicketKeys(keys [][32]byte) {
  	if len(keys) == 0 {
  		panic("tls: keys must have at least one key")
  	}
  
  	newKeys := make([]ticketKey, len(keys))
  	for i, bytes := range keys {
  		newKeys[i] = ticketKeyFromBytes(bytes)
  	}
  
  	c.mutex.Lock()
  	c.sessionTicketKeys = newKeys
  	c.mutex.Unlock()
  }
docs: // SetSessionTicketKeys updates the session ticket keys for a server. The first
  // key will be used when creating new tickets, while all keys can be used for
  // decrypting tickets. It is safe to call this function while the server is
  // running in order to rotate the session ticket keys. The function will panic
  // if keys is empty.