def range_check(low, high):
    """\
    Verifies that that given range has a low lower than the high.
    If the condition is not met, a ValueError is raised.
    Otherwise, the values are returned, but as floats.
    """
    low, high = float(low), float(high)
    if low >= high:
        raise ValueError('low >= high')
    else:
        return low, high