code: def append_vobject(self, vcard, filename=None):
          
          book = ConfigParser(default_section='format')
          with self._lock:
              book.read(self._filename)
              section = str(max([-1] + [int(k) for k in book.sections()]) + 1)
              Abook.to_abook(vcard, section, book, self._filename)
              with open(self._filename, 'w') as fp:
                  book.write(fp, False)
  
          return Abook._gen_uid(book[section])
docs: Appends an address to the Abook addressbook
          vcard -- vCard to append
          filename -- unused
          return the new UID of the appended vcard