In a microservice using a watcher to reload config on changes, what is the expected output?

In a microservice using a watcher to reload config on changes, what is the expected output?

config = {"timeout": 30}
function watchConfig() {
  onChange(newConfig) {
    config = newConfig
  }
}
watchConfig()
// Config update
onChange({"timeout": 45})
print(config["timeout"])