code: func (c *Client) CreateEncryptedWallet(passphrase string) error {
  	return c.CreateEncryptedWalletAsync(passphrase).Receive()
  }
docs: // CreateEncryptedWallet requests the creation of an encrypted wallet.  Wallets
  // managed by btcwallet are only written to disk with encrypted private keys,
  // and generating wallets on the fly is impossible as it requires user input for
  // the encryption passphrase.  This RPC specifies the passphrase and instructs
  // the wallet creation.  This may error if a wallet is already opened, or the
  // new wallet cannot be written to disk.
  //
  // NOTE: This is a btcwallet extension.