orm.go
func OptIndexTrackExistence(trackExistence bool) IndexOption {
	return func(options *IndexOptions) {
		options.trackExistence = trackExistence
		options.trackExistenceSet = true
	}
}
func OptIndexTrackExistence(trackExistence bool) IndexOption {
	return func(options *IndexOptions) {
		options.trackExistence = trackExistence
		options.trackExistenceSet = true
	}
}
func OptIndexTrackExistence ( trackExistence bool ) IndexOption { return func ( options * IndexOptions ) { options . trackExistence = trackExistence options . trackExistenceSet = true } }
// OptIndexTrackExistence enables keeping track of existence of columns.
OptIndexTrackExistence enables keeping track of existence of columns .