Extrinsic 740-1

{
  "heartbeat": {
    "blockNumber": 739,
    "sessionIndex": 12,
    "validatorsLen": 4,
    "authorityIndex": 1
  },
  "signature": "0x8cf2219d3dd059aefd9f884367aace0b25c4888f0c51d5669cd463f56c5fa2470576937a15433db4194ddd51fd6c213806182316078daa23e1e5ef934eba6785"
}