func (o Options) SelectOrder(order []byte) []Option {
	opts := make([]Option, 0, len(order))
	for _, v := range order {
		if data, ok := o[OptionCode(v)]; ok {
			opts = append(opts, Option{Code: OptionCode(v), Value: data})
		}
	}
	return opts
}
SelectOrder returns a slice of options ordered and selected by a byte array
usually defined by OptionParameterRequestList.  This result is expected to be
used in ReplyPacket()'s []Option parameter.
package dhcp4
import (
	"encoding/binary"
	"net"
	"time"
)
func (o Options) SelectOrderOrAll(order []byte) []Option {
	if order == nil {
		opts := make([]Option, 0, len(o))
		for i, v := range o {
			opts = append(opts, Option{Code: i, Value: v})
		}
		return opts
	}
	return o.SelectOrder(order)
}