code: func (*PreparedQueryIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
  	if len(args) != 1 {
  		return nil, fmt.Errorf("must provide only a single argument")
  	}
  	arg, ok := args[0].(string)
  	if !ok {
  		return nil, fmt.Errorf("argument must be a string: %#v", args[0])
  	}
  	arg = "\x00" + strings.ToLower(arg)
  	return []byte(arg), nil
  }
docs: // PrefixFromArgs is used when doing a prefix scan for an object.