How to use the gitdb.base.ODeltaPackInfo function in gitdb

else:
        # assume its a base object
        total_rela_offset = data_rela_offset
    # END handle type id
    abs_data_offset = offset + total_rela_offset
    if as_stream:
        stream = DecompressMemMapReader(buffer(data, total_rela_offset), False, uncomp_size)
        if delta_info is None:
            return abs_data_offset, OPackStream(offset, type_id, uncomp_size, stream)
        else:
            return abs_data_offset, ODeltaPackStream(offset, type_id, uncomp_size, delta_info, stream)
    else:
        if delta_info is None:
            return abs_data_offset, OPackInfo(offset, type_id, uncomp_size)
        else:
            return abs_data_offset, ODeltaPackInfo(offset, type_id, uncomp_size, delta_info)
        # END handle info

else:
        # assume its a base object
        total_rela_offset = data_rela_offset
    # END handle type id
    abs_data_offset = offset + total_rela_offset
    if as_stream:
        stream = DecompressMemMapReader(buffer(data, total_rela_offset), False, uncomp_size)
        if delta_info is None:
            return abs_data_offset, OPackStream(offset, type_id, uncomp_size, stream)
        else:
            return abs_data_offset, ODeltaPackStream(offset, type_id, uncomp_size, delta_info, stream)
    else:
        if delta_info is None:
            return abs_data_offset, OPackInfo(offset, type_id, uncomp_size)
        else:
            return abs_data_offset, ODeltaPackInfo(offset, type_id, uncomp_size, delta_info)
        # END handle info

def __new__(cls, packoffset, type, size, stream, *args):
        """Helps with the initialization of subclasses"""
        return tuple.__new__(cls, (packoffset, type, size, stream))

    #{ Stream Reader Interface
    def read(self, size=-1):
        return self[3].read(size)

    @property
    def stream(self):
        return self[3]
    #} END stream reader interface


class ODeltaPackStream(ODeltaPackInfo):

    """Provides a stream outputting the uncompressed offset delta information"""
    __slots__ = tuple()

    def __new__(cls, packoffset, type, size, delta_info, stream):
        return tuple.__new__(cls, (packoffset, type, size, delta_info, stream))

    #{ Stream Reader Interface
    def read(self, size=-1):
        return self[4].read(size)

    @property
    def stream(self):
        return self[4]
    #} END stream reader interface