def _first_fully_overlapping_windows(mzrs: list) ->list:
    """
    Select m/z windows that fall within another window and have a different mass ranges
    For example: [100-200] and [125-175] (Invalid)

    :param mzrs: Nested list of m/z ranges / windows
    :return: Nested list of m/z ranges / windows
    """
    assert type(mzrs) == list, 'List required'
    for i in range(0, len(mzrs) - 1):
        if mzrs[i][0] <= mzrs[i + 1][0] and mzrs[i][1] >= mzrs[i + 1][1]:
            return mzrs[i], mzrs[i + 1]
    return []
