Walk along an array of asynchronous functions

walk.js

/**
 * walk
 * small function to walk along an array of functions
 * each function walked gets an extra argument
 * that argument is a function that should be called
 * to notify the walk function to step to the next function
 * the arguments given at call time are passed to the next function
 *
 * @function
 * @param {Array} fns Array of functions
 * @returns undefined
 */
function walk(fns) {
    (function next() {
        var args = Array.prototype.slice.call(arguments);
        fns.length && fns.shift().apply(this, args.concat(next));
    }());
}
    
// Usage
function a(input, output, next) {
    // do something asincronous
    // call next when done, and pass values
    // to the next function in line
    next(value1, value2)
}
    
function b(value1, value2, next) {
    // do something asincronous
    // call next when done, and pass values
    // to the next function in line
    next(value1, value2)
}
    
walk([a,b]);