def format_BUILD_MAP_UNPACK_WITH_CALL(oparg):
    """The lowest byte of oparg is the count of mappings, the relative
    position of the corresponding callable f is encoded in the second byte
    of oparg."""
    rel_func_pos, count = divmod(oparg, 256)
    return ("%d mappings, function at %d" % (count, count + rel_func_pos))