code: func Check(req *http.Request, username, password string) bool {
  	auth := parseAuthorizationHeader(req.Header.Get("Authorization"))
  	if auth == nil || auth.username != username {
  		return false
  	}
  	expectedResponse := response(auth, password, req.Method, req.RequestURI)
  	return compare(auth.response, expectedResponse)
  }
docs: // Check returns a bool indicating whether the request is correctly
  // authenticated for the given username and password.