constructor(tickers, logger, exchangeManager, pairConfig) {
    this.tickers = tickers;
    this.logger = logger;
    this.exchangeManager = exchangeManager;
    this.pairConfig = pairConfig;
  }
@param tickers {Tickers}
@param logger {Logger}
@param exchangeManager {ExchangeManager}
@param pairConfig {PairConfig}