code: func GetCSIEndpoint() (network, addr string, err error) {
  	protoAddr := os.Getenv(CSIEndpoint)
  	if emptyRX.MatchString(protoAddr) {
  		return "", "", errors.New("missing CSI_ENDPOINT")
  	}
  	return ParseProtoAddr(protoAddr)
  }
docs: // GetCSIEndpoint returns the network address specified by the
  // environment variable CSI_ENDPOINT.