Stream fiddling - concatenate arrays into functional list, async processing

asyncStack.js

function keyValuePairs(callback) {
  [1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6].forEach(function (i) {
    callback(i);
  });
}

function numbers(callback) {
  for(var i = 0; i < 3; i++) {
    callback([1,2,3]);
  }
}

function individual(stream) {
  return function(callback) {
    stream(function(value) {
      for(var i=0, ii = value.length; i<ii; i++) {
        callback(value[i]);
      }
    });
  };
}

function asyncStack(stream, delay) {
  var list = [],
      timer = null;
  delay = delay || 250;
  return function (callback) {
    var process = function () {
      if(list.length > 0) {
        callback(list.pop());
      } else {
        clearTimeout(timer);
        timer = null;
      }
    };
    stream(function(value) {
      list.push(value);
      timer = timer || setInterval(process, delay);
    });
  };
}

function print(stream) {
  stream(function(v) {
    console.log(v);
  });
}

print(asyncStack(individual(numbers), 100));