How to use the ipdb.util.bytes2long function in ipdb

def _resolve(self, node):
        resolved = node - self._meta.node_count + self._meta.node_count * 8
        size = bytes2long(0, 0, self.data[resolved], self.data[resolved + 1])
        if (resolved+2+size) > len(self.data):
            raise DatabaseError("database is error")
        return self.data[resolved+2:resolved+2+size]

def __init__(self, name):
        self._v4offset = 0
        self._v6offsetCache = {}

        file = open(name, "rb")
        self.data = file.read()
        self._file_size = len(self.data)
        file.close()
        meta_length = bytes2long(self.data[0], self.data[1], self.data[2], self.data[3])
        if sys.version_info < (3,0):
            meta = json.loads(str(self.data[4:meta_length + 4]))
        else:
            meta = json.loads(str(self.data[4:meta_length + 4], 'utf-8'))

        self._meta = MetaData(**meta)
        if len(self._meta.languages) == 0 or len(self._meta.fields) == 0:
            raise DatabaseError("database meta error")
        if self._file_size != (4 + meta_length + self._meta.total_size):
            raise DatabaseError("database size error")

        self.data = self.data[4+meta_length:]

def _read_node(self, node, idx):
        off = idx * 4 + node * 8
        return bytes2long(self.data[off], self.data[off + 1], self.data[off + 2], self.data[off + 3])