curl --request POST \
  --url https://arch-testnet.gomaestro-api.org/v0/rpc/transaction/send/batch \
  --header 'Content-Type: application/json' \
  --header 'api-key: <api-key>' \
  --data '{}'

{
  "data": [
    "<string>"
  ],
  "last_updated": {
    "block_hash": "<string>",
    "block_height": 123
  }
}