Markdown({String data, SyntaxHighlighter syntaxHighlighter, MarkdownStyle markdownStyle, MarkdownLinkCallback onTapLink })

Creates a new Markdown Widget that renders the markdown formatted string passed in as data. By default the markdown will be rendered using the styles from the current theme, but you can optionally pass in a custom markdownStyle that specifies colors and fonts to use. Code blocks are by default not using syntax highlighting, but it's possible to pass in a custom syntaxHighlighter.

new Markdown(data: "Hello _world_!");

Source 

Markdown({
  String data,
  SyntaxHighlighter syntaxHighlighter,
  MarkdownStyle markdownStyle,
  MarkdownLinkCallback onTapLink
}) : super(
  data: data,
  syntaxHighlighter: syntaxHighlighter,
  markdownStyle: markdownStyle,
  onTapLink: onTapLink
);