code: func GetUserClass(o dhcp6.Options) (Data, error) {
  	v, err := o.GetOne(dhcp6.OptionUserClass)
  	if err != nil {
  		return nil, err
  	}
  
  	var d Data
  	err = d.UnmarshalBinary(v)
  	return d, err
  }
docs: // GetUserClass returns the User Class Option value, described in RFC 3315,
  // Section 22.15.
  //
  // The Data structure returned contains any raw class data present in
  // the option.