code: func NewIANA(iaid [4]byte, t1 time.Duration, t2 time.Duration, options dhcp6.Options) *IANA {
  	if options == nil {
  		options = make(dhcp6.Options)
  	}
  
  	return &IANA{
  		IAID:    iaid,
  		T1:      t1,
  		T2:      t2,
  		Options: options,
  	}
  }
docs: // NewIANA creates a new IANA from an IAID, T1 and T2 durations, and an
  // Options map.  If an Options map is not specified, a new one will be
  // allocated.