config.go
func Load(conf interface{}, configPaths ...string) error {
	return loadWithFunc(conf, configPaths, nil, yaml.Unmarshal)
}
func Load(conf interface{}, configPaths ...string) error {
	return loadWithFunc(conf, configPaths, nil, yaml.Unmarshal)
}
// Load loads YAML files from `configPaths`.
// and assigns decoded values into the `conf` value.