[
  {
    "head": {
      "previous_hash": "0000",
      "timestamp": 1234567890,
      "merkle_root": "abc123",
      "block_hash": "def456",
      "nonce": 5
    },
    "tx": [
      {"from": "alice", "to": "bob", "value": 10, "data": ""},
      {"from": "bob", "to": "charlie", "value": 5, "data": ""}
    ]
  }
]