code: function defaults(options) {
    options = options || {};
  
    return {
      reqHeader: options.reqHeader || 'X-Request-Id',
      resHeader: options.resHeader || 'X-Request-Id',
      paramName: options.paramName || 'requestId',
      generator: options.generator || uuid
    };
  }
docs: Initialize Default Options.
  
  @param {Object} options
  Optional configuraiton.
  
  @param {String} [options.reqHeader='X-Request-Id']
  Request Header Name.
  
  @param {String} [options.resHeader='X-Request-Id']
  Response Header Name.
  
  @param {String} [options.paramName='requestId']
  Query Parameter.
  
  @param {Function} [options.generator=uuid]
  Generator Function.
  
  @return {Object}
  Optional configuration.