docs: def need(self, folder, page=None, perpage=None):
          """ Returns lists of files which are needed by this device in order
          for it to become in sync.
  
              Args:
                  folder (str):
                  page (int): If defined applies pagination accross the
                      collection of results.
                  perpage (int): If defined applies pagination across the
                      collection of results.
  
              Returns:
                  dict
          """
          assert isinstance(page, int) or page is None
          assert isinstance(perpage, int) or perpage is None
          return self.get('need', params={'folder': folder,
                                   'page': page,
                                   'perpage': perpage})