unsubscribe (chanId) {
    this.send({
      event: 'unsubscribe',
      chanId: +chanId
    })
  }
Unsubscribe from a channel by ID

@param {number} chanId - ID of channel to unsubscribe from
@example
const id = ws.getDataChannelId('ticker', { symbol: 'tBTCUSD' })

if (id) {
  ws.unsubscribe(id)
}