code: func NewSigncryptArmor62SealStream(ciphertext io.Writer, ephemeralKeyCreator EphemeralKeyCreator, sender SigningSecretKey, receiverBoxKeys []BoxPublicKey, receiverSymmetricKeys []ReceiverSymmetricKey, brand string) (plaintext io.WriteCloser, err error) {
  	return newSigncryptArmor62SealStream(ciphertext, sender, receiverBoxKeys, receiverSymmetricKeys, ephemeralKeyCreator, defaultSigncryptRNG{}, brand)
  }
docs: // NewSigncryptArmor62SealStream creates a stream that consumes plaintext data.
  // It will write out signcrypted data to the io.Writer passed in as ciphertext.
  // The signcryption is from the specified sender, and is signcrypted for the
  // given receivers.
  //
  // The "brand" is the optional "brand" string to put into the header
  // and footer.
  //
  // The ciphertext is additionally armored with the recommended armor62-style format.
  //
  // If initialization succeeds, returns an io.WriteCloser that accepts
  // plaintext data to be signcrypted and a nil error. Otherwise,
  // returns nil and the initialization error.
  //
  // ephemeralKeyCreator should be the last argument; it's the 2nd one
  // to preserve the public API.