def range_check(low, high):
    """\
    Verifies that that given range has a low lower than the high.

        >>> range_check(10, 11)
        (10.0, 11.0)
        >>> range_check(6.4, 30)
        (6.4, 30.0)
        >>> try:
        ...    range_check(7, 2)
        ... except ValueError as e:
        ...    print(e)
        low >= high

    """
    low, high = float(low), float(high)
    if low >= high:
        raise ValueError('low >= high')
    else:
        return low, high