code: func (c *ContentSpec) getMmarkHTMLRenderer(defaultFlags int, ctx *RenderingContext) mmark.Renderer {
  	renderParameters := mmark.HtmlRendererParameters{
  		FootnoteAnchorPrefix:       c.footnoteAnchorPrefix,
  		FootnoteReturnLinkContents: c.footnoteReturnLinkContents,
  	}
  
  	b := len(ctx.DocumentID) != 0
  
  	if ctx.Config == nil {
  		panic(fmt.Sprintf("RenderingContext of %q doesn't have a config", ctx.DocumentID))
  	}
  
  	if b && !ctx.Config.PlainIDAnchors {
  		renderParameters.FootnoteAnchorPrefix = ctx.DocumentID + ":" + renderParameters.FootnoteAnchorPrefix
  		// renderParameters.HeaderIDSuffix = ":" + ctx.DocumentId
  	}
  
  	htmlFlags := defaultFlags
  	htmlFlags |= mmark.HTML_FOOTNOTE_RETURN_LINKS
  
  	return &HugoMmarkHTMLRenderer{
  		cs:       c,
  		Renderer: mmark.HtmlRendererWithParameters(htmlFlags, "", "", renderParameters),
  		Cfg:      c.Cfg,
  	}
  }
docs: // getMmarkHTMLRenderer creates a new mmark HTML Renderer with the given configuration.