//app.js
var client = require('./connection.js')
var commands = require('./commands.js')(client)

// connection.js
// message is equal to client
// so in yours it would be var client = new tmi.Client({Options go here}) then module.exports = client
var message = {
    log: function(message) {
        console.log(message)
    }
}

module.exports = message

// commands.js

// message here is equivilent to client
// message.log is equivilent to client.on
module.exports = function(message) {
    message.log("hello world")
}

//This will log message hello world when you run it.