def show_subnetwork(kwargs=None, call=None):
    '''
    ... versionadded:: 2017.7.0
    Show details of an existing GCE Subnetwork. Must specify name and region.

    CLI Example:

    .. code-block:: bash

        salt-cloud -f show_subnetwork gce name=mysubnet region=us-west1

    '''
    if call != 'function':
        raise SaltCloudSystemExit(
            'The show_subnetwork function must be called with -f or --function.'
        )

    if not kwargs or 'name' not in kwargs:
        log.error(
            'Must specify name of subnet.'
        )
        return False

    if 'region' not in kwargs:
        log.error(
            'Must specify region of subnet.'
        )
        return False

    name = kwargs['name']
    region = kwargs['region']
    conn = get_conn()
    return _expand_item(conn.ex_get_subnetwork(name, region))