code: func GetString(n ast.Node) (string, error) {
  	if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.STRING {
  		return strconv.Unquote(node.Value)
  	}
  	return "", fmt.Errorf("Unexpected AST node type: %T", n)
  }
docs: // GetString will read and return a string value from an ast.BasicLit