something like this

promise-stacks.es7

import request from 'request-promise'

class Task {
    constructor(func){
        this.func = func
        this.deferredTask = null;
    }
    set subTask(task){
        this.deferredTask = task;
    }
    async materialise(...options){
        var result;
        if (this.func instanceof Task){
            result = await this.func.materialise(...result)
        } else {
            result = await this.func(...options)
        }
        if (this.deferredTask instanceof Task){
            return await this.deferredTask.materialise(...result)
        }
        return await this.deferredTask(...result)
    }
}
function a(...options){
    console.log(options)
    return request(...options)
}
async function b(results){
    return await results
}
var aTask = new Task(a({
    gzip: true,
    url: 'http://api.stackexchange.com/2.2/sites'
}));
aTask.subTask = b;
var bTask = new Task(aTask);
bTask.subTask = b;
(async function(){
    let r = await bTask.materialise()
})()