How to use the gitdb.fun.pack_object_header_info function in gitdb

def pack_object_at(cursor, offset, as_stream):
    """
    :return: Tuple(abs_data_offset, PackInfo|PackStream)
        an object of the correct type according to the type_id  of the object.
        If as_stream is True, the object will contain a stream, allowing  the
        data to be read decompressed.
    :param data: random accessible data containing all required information
    :parma offset: offset in to the data at which the object information is located
    :param as_stream: if True, a stream object will be returned that can read
        the data, otherwise you receive an info object only"""
    data = cursor.use_region(offset).buffer()
    type_id, uncomp_size, data_rela_offset = pack_object_header_info(data)
    total_rela_offset = None                # set later, actual offset until data stream begins
    delta_info = None

    # OFFSET DELTA
    if type_id == OFS_DELTA:
        i = data_rela_offset
        c = byte_ord(data[i])
        i += 1
        delta_offset = c & 0x7f
        while c & 0x80:
            c = byte_ord(data[i])
            i += 1
            delta_offset += 1
            delta_offset = (delta_offset << 7) + (c & 0x7f)
        # END character loop
        delta_info = delta_offset

def _object(self, sha, as_stream, index=-1):
        """:return: OInfo or OStream object providing information about the given sha
        :param index: if not -1, its assumed to be the sha's index in the IndexFile"""
        # its a little bit redundant here, but it needs to be efficient
        if index < 0:
            index = self._sha_to_index(sha)
        if sha is None:
            sha = self._index.sha(index)
        # END assure sha is present ( in output )
        offset = self._index.offset(index)
        type_id, uncomp_size, data_rela_offset = pack_object_header_info(self._pack._cursor.use_region(offset).buffer())
        if as_stream:
            if type_id not in delta_types:
                packstream = self._pack.stream(offset)
                return OStream(sha, packstream.type, packstream.size, packstream.stream)
            # END handle non-deltas

            # produce a delta stream containing all info
            # To prevent it from applying the deltas when querying the size,
            # we extract it from the delta stream ourselves
            streams = self.collect_streams_at_offset(offset)
            dstream = DeltaApplyReader.new(streams)

            return ODeltaStream(sha, dstream.type, None, dstream)
        else:
            if type_id not in delta_types:
                return OInfo(sha, type_id_to_type_map[type_id], uncomp_size)

def pack_object_at(cursor, offset, as_stream):
    """
    :return: Tuple(abs_data_offset, PackInfo|PackStream)
        an object of the correct type according to the type_id  of the object.
        If as_stream is True, the object will contain a stream, allowing  the
        data to be read decompressed.
    :param data: random accessible data containing all required information
    :parma offset: offset in to the data at which the object information is located
    :param as_stream: if True, a stream object will be returned that can read
        the data, otherwise you receive an info object only"""
    data = cursor.use_region(offset).buffer()
    type_id, uncomp_size, data_rela_offset = pack_object_header_info(data)
    total_rela_offset = None                # set later, actual offset until data stream begins
    delta_info = None

    # OFFSET DELTA
    if type_id == OFS_DELTA:
        i = data_rela_offset
        c = byte_ord(data[i])
        i += 1
        delta_offset = c & 0x7f
        while c & 0x80:
            c = byte_ord(data[i])
            i += 1
            delta_offset += 1
            delta_offset = (delta_offset << 7) + (c & 0x7f)
        # END character loop
        delta_info = delta_offset