{
  "id": 1,
  "cmd": "subscribe",
  "params": {
    "channels": [
      "orderbook_delta"
    ],
    "market_ticker": "CPI-22DEC-TN0.1"
  }
}

{
  "id": 124,
  "cmd": "unsubscribe",
  "params": {
    "sids": [
      1,
      2
    ]
  }
}

{
  "id": 124,
  "cmd": "update_subscription",
  "params": {
    "sids": [
      456
    ],
    "market_tickers": [
      "NEW-MARKET-1",
      "NEW-MARKET-2"
    ],
    "action": "add_markets"
  }
}

{
  "id": 1,
  "type": "subscribed",
  "msg": {
    "channel": "orderbook_delta",
    "sid": 1
  }
}

{
  "sid": 2,
  "type": "unsubscribed"
}

{
  "id": 123,
  "sid": 456,
  "seq": 222,
  "type": "ok",
  "market_tickers": [
    "MARKET-1",
    "MARKET-2",
    "MARKET-3"
  ]
}

{
  "id": 123,
  "type": "error",
  "msg": {
    "code": 6,
    "msg": "Already subscribed"
  }
}