code: func GetAuthentication(o dhcp6.Options) (*Authentication, error) {
  	v, err := o.GetOne(dhcp6.OptionAuth)
  	if err != nil {
  		return nil, err
  	}
  
  	a := new(Authentication)
  	err = a.UnmarshalBinary(v)
  	return a, err
  }
docs: // GetAuthentication returns the Authentication Option value, as described in
  // RFC 3315, Section 22.11.
  //
  // The Authentication option carries authentication information to
  // authenticate the identity and contents of DHCP messages.