onTradeEntry ({ pair, symbol, cbGID }, cb) {
    const id = pair || symbol || ''
    this._registerListener('trade-entry', { 0: id }, PublicTrade, cbGID, cb)
  }
Register a handler to be called on each trade `'te'` event

@param {object} opts - options
@param {string} [opts.pair] - required if no symbol specified
@param {string} [opts.symbol] - required if no pair specified
@param {string|number} [opts.cbGID] - callback group id
@param {Function} cb - callback
@see https://docs.bitfinex.com/v2/reference#ws-public-trades
@see WSv2#subscribeTrades
@see WSv2#unsubscribeTrades