docs: function Stweam(opts) {
    stream.Transform.call(this);
    opts = opts || {};
    if (!opts.consumerKey) throw new Error('consumer key is required');
    if (!opts.consumerSecret) throw new Error('consumer secret is required');
    if (!opts.token) throw new Error('token is required');
    if (!opts.tokenSecret) throw new Error('token secret is required');
    this.consumerKey = opts.consumerKey;
    this.consumerSecret = opts.consumerSecret;
    this.token = opts.token;
    this.tokenSecret = opts.tokenSecret;
    this._keywords = '';
    this._language = 'en';
    this._follow = '';
    this._initBackoffs();
  }