How to use the @instana/core.logger function in @instana/core

if (process.env['INSTANA_DEBUG']) {
      parentLogger.level('debug');
    } else if (config.level) {
      parentLogger.level(config.level);
    } else if (process.env['INSTANA_LOG_LEVEL']) {
      parentLogger.level(process.env['INSTANA_LOG_LEVEL'].toLowerCase());
    }
  }

  if (isReInit) {
    Object.keys(registry).forEach(function(loggerName) {
      var reInitFn = registry[loggerName];
      reInitFn(exports.getLogger(loggerName));
    });
    // cascade re-init to @instana/core
    instanaNodeJsCore.logger.init(config);
  }
};

exports.setLogger = function setLogger(logger) {
  config.logger = logger;
  instanaCore.logger.init(config);
};

exports.setLogger = function setLogger(_logger) {
  logger = _logger;
  config.logger = logger;
  instanaCore.logger.init(config);
};