code: func GetRapidCommit(o dhcp6.Options) error {
  	v, err := o.GetOne(dhcp6.OptionRapidCommit)
  	if err != nil {
  		return err
  	}
  
  	// Data must be completely empty; presence of the Rapid Commit option
  	// indicates it is requested.
  	if len(v) != 0 {
  		return dhcp6.ErrInvalidPacket
  	}
  	return nil
  }
docs: // GetRapidCommit returns the Rapid Commit Option value, described in RFC 3315,
  // Section 22.14.
  //
  // Nil is returned if OptionRapidCommit was present in the Options map.