function remarkGfm(options) {
  // @ts-expect-error: TS is wrong about `this`.
  // eslint-disable-next-line unicorn/no-this-assignment
  const self = /** @type {Processor<Root>} */ (this)
  const settings = options || emptyOptions
  const data = self.data()

  const micromarkExtensions =
    data.micromarkExtensions || (data.micromarkExtensions = [])
  const fromMarkdownExtensions =
    data.fromMarkdownExtensions || (data.fromMarkdownExtensions = [])
  const toMarkdownExtensions =
    data.toMarkdownExtensions || (data.toMarkdownExtensions = [])

  micromarkExtensions.push(gfm(settings))
  fromMarkdownExtensions.push(gfmFromMarkdown())
  toMarkdownExtensions.push(gfmToMarkdown(settings))
}
Add support GFM (autolink literals, footnotes, strikethrough, tables,
tasklists).

@param {Options | null | undefined} [options]
  Configuration (optional).
@returns {undefined}
  Nothing.