text: from typing import List
  from collections import namedtuple
  from .schema import SchemaMeta, OptionKey
  
  FriendLink = namedtuple('FriendLink', ['name', 'link'])
  
  
  class Site(metaclass=SchemaMeta):
      title = OptionKey(str)
      author = OptionKey(str)
      contact = OptionKey(dict)
      description = OptionKey(str)
      friends = OptionKey(List[FriendLink])
  