How to use the @aws-crypto/client-node.MultiKeyringNode function in @aws-crypto/client-node

* and a namespace for raw encryption key providers.
   * The name and namespace that you use in the decryption keyring *must* be an exact,
   * *case-sensitive* match for the name and namespace in the encryption keyring.
   */
  const keyName = 'aes-name'
  const keyNamespace = 'aes-namespace'
  /* The wrapping suite defines the AES-GCM algorithm suite to use. */
  const wrappingSuite = RawAesWrappingSuiteIdentifier.AES256_GCM_IV12_TAG16_NO_PADDING
  // Get your plaintext master key from wherever you store it.
  const unencryptedMasterKey = randomBytes(32)

  /* Configure the Raw AES Keyring. */
  const aesKeyring = new RawAesKeyringNode({ keyName, keyNamespace, unencryptedMasterKey, wrappingSuite })

  /* Combine the two keyrings with a MultiKeyring. */
  const keyring = new MultiKeyringNode({ generator: kmsKeyring, children: [ aesKeyring ] })

  /* Encryption context is a *very* powerful tool for controlling and managing access.
   * It is ***not*** secret!
   * Encrypted data is opaque.
   * You can use an encryption context to assert things about the encrypted data.
   * Just because you can decrypt something does not mean it is what you expect.
   * For example, if you are are only expecting data from 'us-west-2',
   * the origin can identify a malicious actor.
   * See: https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
   */
  const context = {
    stage: 'demo',
    purpose: 'simple demonstration app',
    origin: 'us-west-2'
  }

export function decryptMaterialsManagerNode (keyInfos: KeyInfoTuple[]) {
  const children = keyInfos.map(keyringNode)
  return new MultiKeyringNode({ children })
}

export function encryptMaterialsManagerNode (keyInfos: KeyInfoTuple[]) {
  const [generator, ...children] = keyInfos.map(keyringNode)
  return new MultiKeyringNode({ generator, children })
}