def sanitize_network(network, ip_version):
    """
    :return: Network string
    :rtype: str
    :raises ValueError: if the network string is invalid.
    """

    import ipaddress

    if typepy.is_null_string(network) or network.lower() == "anywhere":
        return get_anywhere_network(ip_version)

    try:
        if ip_version == 4:
            ipaddress.IPv4Address(network)
            return network + "/32"

        if ip_version == 6:
            return ipaddress.IPv6Address(network).compressed
    except ipaddress.AddressValueError:
        pass

    # validate network str ---

    if ip_version == 4:
        return ipaddress.IPv4Network(six.text_type(network)).compressed

    if ip_version == 6:
        return ipaddress.IPv6Network(six.text_type(network)).compressed

    raise ValueError("unexpected ip version: {}".format(ip_version))
:return: Network string
    :rtype: str
    :raises ValueError: if the network string is invalid.