code: def get_common_parts(r):
      
  
      title = format_title(r.get('title'))
      author_list = format_author_list(r.get('author'))
      container = format_container(r.get('container-title'))
      date = format_date(r.get('issued'))
      doi = r.get('DOI')
  
      return Parts(type='Unknown', title=title, authors=author_list, container=container, date=date, extra='', doi=doi)
docs: Gets citation parts which are common to all types of citation