code: def origin(hosts):
      
  
      hosts = [urlsplit(h) for h in hosts]
  
      def func(environ):
          if 'ISSO_CORS_ORIGIN' in environ:
              return environ['ISSO_CORS_ORIGIN']
  
          if not hosts:
              return "http://invalid.local"
  
          loc = environ.get("HTTP_ORIGIN", environ.get("HTTP_REFERER", None))
  
          if loc is None:
              return urljoin(*hosts[0])
  
          for split in hosts:
              if urlsplit(loc) == split:
                  return urljoin(*split)
          else:
              return urljoin(*hosts[0])
  
      return func
docs: Return a function that returns a valid HTTP Origin or localhost
      if none found.