Extrinsic 975-1

{
  "heartbeat": {
    "blockNumber": 973,
    "sessionIndex": 16,
    "validatorsLen": 1,
    "authorityIndex": 0
  },
  "signature": "0xd4feba2378d57053d85f2d40d8784f1c9bd772fd061cfc6ee4c6b57fa2a80e636efb01464bac905a39089ea04d5ba846e002bc99c353ccd1578d6b675060c980"
}