query.go
func SelectMany(subject Enumerable, toMany Unfolder) Enumerable {
	return selectManyer{
		original: subject,
		toMany:   toMany,
	}
}
func SelectMany(subject Enumerable, toMany Unfolder) Enumerable {
	return selectManyer{
		original: subject,
		toMany:   toMany,
	}
}
func SelectMany ( subject Enumerable , toMany Unfolder ) Enumerable { return selectManyer { original : subject , toMany : toMany , } }
// SelectMany allows for unfolding of values.
SelectMany allows for unfolding of values .