async subscribeCandles (key) {
    return this.managedSubscribe('candles', key, { key })
  }
Subscribe to a candle data channel

@param {string} key - 'trade:5m:tBTCUSD'
@returns {boolean} subscribed
@see WSv2#managedSubscribe
@example
await ws.subscribeCandles('trade:5m:tBTCUSD')