opstream.js
function (options) {
  options = options || {};
  this.maxLen = options.maxLen || 20; //how many packets can be buffered before stopping acknowledging new packets
  this.ops = [];
  this.seq = 0;
  this.drained = true;
  this._send = function (op) {
  };
}
function (options) {
  options = options || {};
  this.maxLen = options.maxLen || 20; //how many packets can be buffered before stopping acknowledging new packets
  this.ops = [];
  this.seq = 0;
  this.drained = true;
  this._send = function (op) {
  };
}
/*
Receiver stream