class_docstr: This custom Renderer is heavily based on the `MarkdownRenderer`,
  it just prepends a front matter so that the output can be published
  directly to readme.io.
class_docstr_tok: ["This","custom","Renderer","is","heavily","based","on","the","`","MarkdownRenderer","`",",","it","just","prepends","a","front","matter","so","that","the","output","can","be","published","directly","to","readme.io","."]
code: def _frontmatter(self) -> str:
      return README_FRONTMATTER.format(
          title=self.title,
          category=self.categories[self.category_slug],
          parent_doc=self._doc_id(self.parent_doc_slug, self.version),
          excerpt=self.excerpt,
          slug=self.slug,
          order=self.order,
      )
  
imports: import os
  import sys
  import io
  import dataclasses
  import typing
  import base64
  import warnings
  from pathlib import Path
  import requests
  import docspec
  from pydoc_markdown.interfaces import Context, Renderer
  from pydoc_markdown.contrib.renderers.markdown import MarkdownRenderer
label_desc: Use image node_id 6 for calling the ReadmeRenderer obj's underlying member method code with example usage: obj._frontmatter() and returns: README_FRONTMATTER