#4, добавила роутер /users

app/users.js

+const express = require("express");
+const User = require("../models/User");
+
+const createRouter = () => {
+  const router = express.Router();
+
+  router.get("/", async (req, res) => {
+    try {
+      res.send(await User.find());
+    } catch (e) {res.status(500).send(e)}
+  });
+
+  router.post("/", async (req, res) => {
+    const user = new User(req.body);
+    try {
+      await user.save();
+      res.send(user);
+    } catch (e) {res.status(400).send(e)}
+  });
+
+  router.post("/sessions", async (req, res) => {
+    const user = await User.findOne({username: req.body.username});
+
+    if (!user) {
+      return res.status(400).send({error: "Username not found"});
+    }
+
+    const isMatch = await user.checkPassword(req.body.password);
+
+    if (!isMatch) {
+      return res.status(400).send({error: "Wrong password"});
+    }
+
+    user.generateToken();
+
+    await user.save();
+
+    res.send(user);
+
+  });
+
+  router.delete("/sessions", async (req, res) => {
+    const token = req.get("Token");
+    const success = {message: "Success"};
+
+    if (!token) return res.send(success);
+
+    const user = await User.findOne({token});
+
+    if (!user) return res.send(success);
+
+    user.generateToken();
+    await user.save()
+
+    res.send(success);
+
+  });
+
+  return router;
+};
+
+module.exports = createRouter;