add example_test.go

readme.md

@@ -1,6 +1,6 @@
 [![GoDoc](https://pkg.go.dev/badge/github.com/mojocn/sseread?status.svg)](https://pkg.go.dev/github.com/mojocn/sseread?tab=doc)
 [![Go Report Card](https://goreportcard.com/badge/github.com/mojocn/sseread?)](https://goreportcard.com/report/github.com/mojocn/sseread)
-[![codecov](https://codecov.io/gh/mojocn/sseread/branch/master/graph/badge.svg)](https://codecov.io/gh/mojocn/sseread)
+[![codecov](https://codecov.io/gh/mojocn/sseread/graph/badge.svg?token=3UC1L5K4LY)](https://codecov.io/gh/mojocn/sseread)
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