Extrinsic 151225-1

{
  "heartbeat": {
    "blockNumber": 151224,
    "sessionIndex": 2520,
    "validatorsLen": 1,
    "authorityIndex": 0
  },
  "signature": "0x96ea1ef93feeaac31244360132fc25380dccd26d58204d9527f39b34087afb27f9d10fde7b8da2e7a5347956faf45c4aed8f6da0da2c6c6f5073b3343b7f7983"
}