code: func decodeJWT(a ast.Value) (*JSONWebToken, error) {
  	// Parse the JSON Web Token
  	astEncode, err := builtins.StringOperand(a, 1)
  	if err != nil {
  		return nil, err
  	}
  
  	encoding := string(astEncode)
  	if !strings.Contains(encoding, ".") {
  		return nil, errors.New("encoded JWT had no period separators")
  	}
  
  	parts := strings.Split(encoding, ".")
  	if len(parts) != 3 {
  		return nil, fmt.Errorf("encoded JWT must have 3 sections, found %d", len(parts))
  	}
  
  	return &JSONWebToken{header: parts[0], payload: parts[1], signature: parts[2]}, nil
  }
docs: // -- Utilities --