code: def parse_ns_headers(ns_headers):
      
      known_attrs = ("expires", "domain", "path", "secure",
                     # RFC 2109 attrs (may turn up in Netscape cookies, too)
                     "version", "port", "max-age")
  
      result = []
      for ns_header in ns_headers:
          pairs = []
          version_set = False
          for ii, param in enumerate(re.split(r";\s*", ns_header)):
              param = param.rstrip()
              if param == "": continue
              if "=" not in param:
                  k, v = param, None
              else:
                  k, v = re.split(r"\s*=\s*", param, 1)
                  k = k.lstrip()
              if ii != 0:
                  lc = k.lower()
                  if lc in known_attrs:
                      k = lc
                  if k == "version":
                      # This is an RFC 2109 cookie.
                      v = strip_quotes(v)
                      version_set = True
                  if k == "expires":
                      # convert expires date to seconds since epoch
                      v = http2time(strip_quotes(v))  # None if invalid
              pairs.append((k, v))
  
          if pairs:
              if not version_set:
                  pairs.append(("version", "0"))
              result.append(pairs)
  
      return result
docs: Ad-hoc parser for Netscape protocol cookie-attributes.
  
      The old Netscape cookie format for Set-Cookie can for instance contain
      an unquoted "," in the expires field, so we have to use this ad-hoc
      parser instead of split_header_words.
  
      XXX This may not make the best possible effort to parse all the crap
      that Netscape Cookie headers contain.  Ronald Tschalar's HTTPClient
      parser is probably better, so could do worse than following that if
      this ever gives any trouble.
  
      Currently, this is also used for parsing RFC 2109 cookies.