code: def group_authenticated(self, user_token, group):
          
          if self.authenticated(user_token):
              token = self.token_storage.get(user_token)
              groups = self.get_groups(token.username)
              if group in groups:
                  return True
  
          return False
docs: Checks if user represented by token is in group.
  
          :param user_token: string representing token
  
          :param group: group's name