Function cb

packages/engine.io/test/server.js:2724–2730

(value)

            });

            function cb(value) {
              expect(value).to.eql(lastCbFired + 1);
              lastCbFired = value;
              if (value === 3) {
                done();
              }
            }

            // 2 and 3 will be in the same payload
            socket.once("flush", () => {