类型如何间接引用其他函数的基本方法？

First of all, I am still not clear how to frame this question, but I am not able to understand, can someone help me in understanding this. Why does the below code errors out if I rename "serveHTTP" or not have that method.

prog.go:17: cannot use &status (type *statusHandler) as type http.Handler in argument to httptest.NewServer:
*statusHandler does not implement http.Handler (missing ServeHTTP method)
[process exited with non-zero status]

for the below code

type statusHandler int

func (s *statusHandler) aServeHTTP(w http.ResponseWriter, r *http.Request) {
    log.Println(" inside status handler serve http")
}

func main() {
    status := statusHandler(400)
    s := httptest.NewServer(&status)
    log.Println("value of s is %d", s)
    defer s.Close()
}

http://play.golang.org/p/QZIrWALAm_

ServeHTTP is required to satisfy the http.Handler interface.

type Handler interface {
        ServeHTTP(ResponseWriter, *Request)
}

Interfaces in Go provide a way to specify the behavior of an object: if something can do this, then it can be used here.

See Interfaces and Types in Effective Go for more info.