How to use the @storefront-api/lib/elastic.getClient function in @storefront-api/lib

return new Promise((resolve, reject) => {
      inst.applyTierPrices(productList, groupId)

      if (this._config.tax.calculateServerSide) {
        const client = es.getClient(this._config)
        const esQuery = es.adjustQuery({
          index: this._indexName,
          body: bodybuilder()
        }, 'taxrule', this._config)
        client.search(esQuery).then((body) => { // we're always trying to populate cache - when online
          inst._taxClasses = es.getHits(body).map(el => { return el._source })
          for (let item of productList) {
            const isActive = checkIfTaxWithUserGroupIsActive(inst._storeConfigTax)
            if (isActive) {
              groupId = getUserGroupIdToUse(inst._userGroupId, inst._storeConfigTax)
            } else {
              groupId = null
            }

            inst.taxFor(item._source, groupId)
          }

return new Promise((resolve, reject) => {
      inst.applyTierPrices(productList, groupId)

      if (this._config.tax.calculateServerSide) {
        const client = es.getClient(this._config)
        const esQuery = es.adjustQuery({
          index: this._indexName,
          body: bodybuilder()
        }, 'taxrule', this._config)

        client.search(esQuery).then((result) => { // we're always trying to populate cache - when online
          inst._taxClasses = es.getHits(result).map(el => { return el._source })
          for (let item of productList) {
            const isActive = checkIfTaxWithUserGroupIsActive(inst._storeConfigTax)
            if (isActive) {
              groupId = getUserGroupIdToUse(inst._userGroupId, inst._storeConfigTax)
            } else {
              groupId = null
            }

            inst.taxFor(item._source, groupId)