code: function Endo(api) {
    if (api instanceof Endo) {
      return api;
    }
  
    if (!(this instanceof Endo)) {
      return new Endo(api);
    }
  
    this.endpoints = util.parse(api);
    this.source = api;
    this.version = api.version;
  
    //
    // copy default resposne headers for each instance
    //
    this.responseHeaders = xtend(this.responseHeaders);
  }
docs: endpoint handler