def _import_multi(paths, pattern):
    assert_is_type(paths, [str])
    assert_is_type(pattern, str, None)
    j = api("POST /3/ImportFilesMulti", {"paths": paths, "pattern": pattern})
    if j["fails"]: raise ValueError("ImportFiles of '" + ".".join(paths) + "' failed on " + str(j["fails"]))
    return j["destination_frames"]