/// <summary>
/// 异步执行一个获取递增列值的命令模型。
/// </summary>
/// <typeparam name="TEntity">实体的数据类型。</typeparam>
/// <param name="bus">命令总线。</param>
/// <param name="tunnel">用于个性化表名和命令的暗道，可以为 null 值。</param>
/// <returns>递增列值。</returns>
public static Task <long> GetIdentityAsync <TEntity>(this ICommandBus bus, ICommandTunnel tunnel = null)
=> bus.CallAsync(new CMD.GetIdentity <TEntity>()
{
Tunnel = tunnel
});
/// <summary>
/// 异步执行一个添加的命令模型。
/// </summary>
/// <typeparam name="TEntity">实体的数据类型。</typeparam>
/// <param name="bus">命令总线。</param>
/// <param name="entity">实体的实例。</param>
/// <param name="tunnel">用于个性化表名和命令的暗道，可以为 null 值。</param>
/// <returns>受影响的行。</returns>
public static Task <int> AddAnonymousAsync <TEntity>(this ICommandBus bus, object entity, ICommandTunnel tunnel = null)
=> bus.CallAsync(new CMD.Add <TEntity>()
{
Entity = entity, Tunnel = tunnel
});