How to build a chain to manage all subsequent tasks? If we have a set of N tasks in some cases, then we should call `then(fn)` N -1 times, right?

gistfile1.js

TaskBuilder.prototype.falldown = function(func, handler) {
  var self = this;

  Q.fcall(func).then(function(cb) {
    return function(next) {
      cb(function(fn, args) {
        fn(args, next);
      });
    };
  }).then(function(cb) {
    return function(next) {
      cb(function() {
        if(_.isFunction(arguments[0])) {
          var fn = arguments[0];
          fn(arguments[1], next);
        } else {
          self.send(handler, arguments[0]);
        }
      });
    };
  }).then(function(cb) {
    cb(function() {
      self.send(handler, arguments[0]);
    });
  }).done();
};

TaskBuilder.prototype.send = function(f, args, cb) {
  this.stack.push(args);
  if (this.stack.length == this.nodes.length) {
    f({
      status: 'ok',
      nodes: this.stack
    });

    if(cb) cb();
  }
};