I have two collections tutors and users in my database mongodb. I have a signin function in the controller. Inside signin I have tutors and users. What condition should I add so that it searches for a user in both the tutors and users collections?
controllers/auth
const User = require('../models/user');
const Tutor = require('../models/tutor');
module.exports.signin = (req, res) => {
    const {email, password, remember} = req.body;
    //User
    User.findOne({email}).exec((err, user) => {
        if(err || !user) {
            return res.status(400).json({
                error: 'User with that email does not exist. Please signup'
            });
        }
        if(!user.authenticate(password)) {
            return res.status(400).json({
                error: 'Email and password do not match'
            });
        }
        const {_id, name, surname, email} = user;
        if (remember) {
            const token = jwt.sign({_id: user._id}, process.env.JWT_SECRET, {expiresIn: '7d'});
            return res.json({
                token,
                user: {_id, name, surname, email}
            });
          } else {
            const token = jwt.sign({_id: user._id}, process.env.JWT_SECRET, {expiresIn: '2m'});
            return res.json({
                token,
                user: {_id, name, surname, email}
            });
        }
    });
//tutor
Tutor.findOne({email}).exec((err, tutor) => {
        if(err || !tutor) {
            return res.status(400).json({
                error: 'Tutor with that email does not exist. Please signup'
            });
        }
        if(!tutor.authenticate(password)) {
            return res.status(400).json({
                error: 'Email and password do not match'
            });
        }
        const {_id, name, surname, email} = tutor;
        if (remember) {
            const token = jwt.sign({_id: user._id}, process.env.JWT_SECRET, {expiresIn: '7d'});
            return res.json({
                token,
                tutor: {_id, name, surname, email}
            });
          } else {
            const token = jwt.sign({_id: tutor._id}, process.env.JWT_SECRET, {expiresIn: '2m'});
            return res.json({
                token,
                tutor: {_id, name, surname, email}
            });
        }
    });
};