orm.go
func NewIndex(name string) *Index {
	options := &IndexOptions{}
	return &Index{
		name:    name,
		options: options.withDefaults(),
		fields:  map[string]*Field{},
	}
}
func NewIndex(name string) *Index {
	options := &IndexOptions{}
	return &Index{
		name:    name,
		options: options.withDefaults(),
		fields:  map[string]*Field{},
	}
}
// NewIndex creates an index with a name.