def METHOD_NAME(chemsys) -> Set:
    # Function to get all relevant chemical subsystems
    # e.g. for Li-Mn-O returns Li, Li-Mn, Li-Mn-O, Li-O, Mn, Mn-O, O
    elements = chemsys.split("-")
    return {
        "-".join(sorted(c))
        for c in chain(
            *[combinations(elements, i) for i in range(1, len(elements) + 1)]
        )
    }