code: def build_base_document(dom, return_fragment=True):
      
      body_element = dom.find(".//body")
  
      if body_element is None:
          fragment = fragment_fromstring('<div id="readabilityBody"/>')
          fragment.append(dom)
      else:
          body_element.tag = "div"
          body_element.set("id", "readabilityBody")
          fragment = body_element
  
      return document_from_fragment(fragment, return_fragment)
docs: Builds a base document with the body as root.
  
      :param dom: Parsed lxml tree (Document Object Model).
      :param bool return_fragment: If True only <div> fragment is returned.
          Otherwise full HTML document is returned.