:return:
            array of file objects (200 status code)

def all(self):
        """
        :return:
            array of file objects (200 status code)
        """
        url = "{url_base}/resource/{pid}/files/".format(url_base=self.hs.url_base,
                                                                 pid=self.pid)
        r = self.hs._request('GET', url)
        return r