SOURCE

function people(name){
    this.name = name
    let queue = []
    let status = 'waiting'

    const execute = function(){
        let task = queue.shift()
        while(task){
            // console.log(task)
            task()
            task = queue.shift()
        }
    }

    this.work = function(){
        queue.push(()=> {
            console.log("I'm working")
        })
        // if(status == 'waiting'){
        //     execute()
        // }
        return this
    }
    this.eat = function(food){
        queue.push(()=> {
            console.log("I'm eating "+ food)
        })
        // if(status == 'waiting'){
        //     execute()
        // }
        return this
    }
    this.sleep = function(delay){
        status = 'pending'
        setTimeout(()=>{
            status = 'waiting'
            console.log('deal ' + delay + ' seconds later')
            // execute()
        }, delay * 1000)
        return this
    }
    this.sleepBefore = function(delay){
        console.log('start ' + delay + ' seconds later')
        
    }


        if(status == 'waiting'){
            execute()
        }    
    return this
}

people('david').work().sleep(3).eat('banana').sleepBefore(5)