pkg/relabel/relabel.go
func (re Regexp) MarshalYAML() (interface{}, error) {
	if re.original != "" {
		return re.original, nil
	}
	return nil, nil
}
func (re Regexp) MarshalYAML() (interface{}, error) {
	if re.original != "" {
		return re.original, nil
	}
	return nil, nil
}
// MarshalYAML implements the yaml.Marshaler interface.