C#에서 편집

    // Specify the path to the source MD file
    var input = @"C:\temp\document.md";

    // Create a MarkdownParser object
    var parser = new MarkdownParser();

    // Parse the MD document and get a syntax tree
    var syntaxTree = parser.ParseFile(input);

    // Get a SyntaxFactory to create new elements 
    var syntaxFactory = syntaxTree.SyntaxFactory;

    // Create a new paragraph 
    var paragraphSyntaxNode = syntaxFactory.Paragraph();

    // Create and add newLineTrivia element for an empty line after paragraph 
    var newLineTrivia = syntaxFactory.NewLineTrivia();
    paragraphSyntaxNode.GetTrailingTrivia().Add(newLineTrivia);
            
    // Create text content for the paragraph 
    var textSyntaxNode = syntaxFactory.Text("New paragraph text.");
    paragraphSyntaxNode.AppendChild(textSyntaxNode);

    // Add the paragraph before the first element of the syntax tree
    syntaxTree.InsertBefore(paragraphSyntaxNode, syntaxTree.FirstChild);

    // Prepare a path for MD file saving 
    string savePath = Path.Combine(OutputDir, "output-add-paragraph.md");

    // Save MD file
    syntaxTree.Save(savePath);

    // Specify the path to the source MD file
    var input = @"C:\temp\document.md";

    // Create a MarkdownParser object
    var parser = new MarkdownParser();

    // Parse the MD document and get a syntax tree
    var syntaxTree = parser.ParseFile(input);

    // The first element of this document is AtxHeading
    var heading = (AtxHeadingSyntaxNode)syntaxTree.FirstChild;

    // Accumulate the text content from its elements
    var sb = new StringBuilder();

    while (heading.FirstChild != null)
    {
        sb.Append(heading.FirstChild);

        //  Remove accumulated first element from the tree
        heading.RemoveChild(heading.FirstChild);
    }

    // Get a SyntaxFactory to create new elements 
    var syntaxFactory = syntaxTree.SyntaxFactory;

    // Сreate a text node consisting of new and old text and add it as a child element of AtxHeading 
    var textSyntaxNode = syntaxFactory.Text("Some new text! " + sb);
            
    // Add the new element to the document tree
    heading.AppendChild(textSyntaxNode);

    // Prepare a path for MD file saving 
    string savePath = Path.Combine(OutputDir, "output-edit-header.md");

    // Save MD file
    syntaxTree.Save(savePath);