docs: function createInstanceAsync(service_uuid, opts, callback) {
      assert.string(service_uuid, 'service_uuid');
      if (typeof (opts) === 'function') {
          callback = opts;
          opts = {};
      }
      assert.object(opts, 'opts');
      assert.func(callback, 'callback');
  
      opts.service_uuid = service_uuid;
  
      return (this.post('/instances?async=true', opts, callback));
  }