record.go
func (r Record) Columns() []string {
	cols := []string{}
	for k := range r {
		cols = append(cols, k)
	}
	sort.Strings(cols)

	return cols
}
func (r Record) Columns() []string {
	cols := []string{}
	for k := range r {
		cols = append(cols, k)
	}
	sort.Strings(cols)

	return cols
}
// Columns returns the list of the record columns.