co_and_generator.js

import co from 'co';
app.post("/purchase", (req, res) => {
    co(function* () {
        const person = yield user.findOneAsync(req.body);
        const permissions = yield permissions.findAllAsync(person);
        if (isAllowed(permissions)) {
            const confirmNum = yield transaction.processAsync(user);
            res.send("Your transaction was successful!")
        }
    }).catch(err => handleError(err))
});