'get two list, each list contains two elements: name and nd.array value'

def _read(self):

    (_, data_img_name, label_img_name) = self.f.readline().strip('\n').split(' DCTB ')
    data = {}
    label = {}
    (data[self.data_name], label[self.label_name]) = self._read_img(data_img_name, label_img_name)
    return (list(data.items()), list(label.items()))
