How to use the presto-client.Client function in presto-client

this.config = {
      host: process.env.CUBEJS_DB_HOST,
      port: process.env.CUBEJS_DB_PORT,
      catalog: process.env.CUBEJS_DB_CATALOG,
      schema: process.env.CUBEJS_DB_SCHEMA,
      user: process.env.CUBEJS_DB_USER,
      basic_auth: process.env.CUBEJS_DB_PASS ? {
        user: process.env.CUBEJS_DB_USER,
        password: process.env.CUBEJS_DB_PASS
      } : undefined,
      ...config
    };

    this.catalog = this.config.catalog;
    this.client = new presto.Client(this.config);
  }

var Executer = exports.Executer = function(conf, logger){
  if (conf.name !== 'presto')
    throw "executer name mismatch for presto:" + conf.name;
  if (!conf.host)
    throw "host MUST be specified for presto executer";
  if (!conf.port)
    throw "port MUST be specified for presto executer";
  if (!conf.catalog)
    throw "catalog MUST be specified for presto executer";

  this.logger = logger;
  this._client = new Client({
    host: conf.host,
    port: conf.port,
    user: conf.user,
    catalog: conf.catalog,
    jsonParser: JSONbig
  });
};