How to set cookie on websocket connection in Impress?

Question

Node.js

Good afternoon.
I am rewriting the application under Impress. Before using Impress, there was something like

var wss = require('ws').createServer();
wss.on('headers', (headers) => {
  headers.push('Set-Cookie: myTestCookie=testValue');
});

In \connect.ws\get.js, this cannot be done by itself, since it is too late to set the cookie at this stage. Can you please tell me how to do this on Impress?