docs: def parse_auth(header):
      """ Parse rfc2617 HTTP authentication header string (basic) and return (user,pass) tuple or None"""
      try:
          method, data = header.split(None, 1)
          if method.lower() == 'basic':
              user, pwd = touni(base64.b64decode(tob(data))).split(':',1)
              return user, pwd
      except (KeyError, ValueError):
          return None