docs: def parse_nondisclosure_deadline(content):
      """\
      Returns the non-disclosure deadline if provided, otherwise ``None``.
      Format of the returned string: ``YYYY-MM-DD``.
  
      `content`
          The cable's content.
      """
      m = _DEADLINE_PATTERN.search(content)
      if not m:
          return None
      p1, p2 = m.groups()
      if p1:
          month, day, year = p1.split(u'/')
          if len(year) != 4:
              year = 2000 + int(year)
          month = month.zfill(2)
          day = day.zfill(2)
      else:
          year, month, day = p2.split(u'/')
      return u'%s-%s-%s' % (year, month, day)