func (n Nag) Description() string {
	if int(n) >= len(nagData) {
		return fmt.Sprintf("$%d: non-standard NAG", n)
	}
	return nagData[n].desc
}
Description returns a short description explaining the NAG.
package pgn
import (
	"fmt"
)
type Nag int
func (n Nag) String() string {
	if int(n) >= len(nagData) || nagData[n].str == "" {
		return fmt.Sprintf("$%d", n)
	}
	return nagData[n].str
}