code: function WPCOMUndocumented( token, reqHandler ) {
  	if ( ! ( this instanceof WPCOMUndocumented ) ) {
  		return new WPCOMUndocumented( token, reqHandler );
  	}
  
  	if ( 'function' === typeof token ) {
  		reqHandler = token;
  		token = null;
  	} else if ( token ) {
  		this.loadToken( token );
  	}
  
  	wpcomFactory.call( this, token, function( params, fn ) {
  		if ( this.isTokenLoaded() ) {
  			// authToken is used in wpcom-xhr-request,
  			// which is used for the signup flow in the REST Proxy
  			params = assign( {}, params, { authToken: this._token, token: this._token } );
  		}
  
  		return reqHandler( params, fn );
  	} );
  
  	debug( 'Extending wpcom with undocumented endpoints.' );
  }
docs: Class inherited from `WPCOMUnpublished` class and adds
  specific methods useful for wp-calypso.
  
  @param {String} [token] - oauth token
  @param {Function} [reqHandler] - request handler
  @return {NUll} null