Posting to an ActionBlock and waiting for completion

// Create a block with an asynchronous action
var block = new ActionBlock<string>(async hostName =>
{
    IPAddress[] ipAddresses = await Dns.GetHostAddressesAsync(hostName);
    Console.WriteLine(ipAddresses[0]);
});

block.Post("google.com"); // Post items to the block's InputQueue for processing
block.Post("reddit.com");
block.Post("stackoverflow.com");

block.Complete(); // Tell the block to complete and stop accepting new items
await block.Completion; // Asynchronously wait until all items completed processingu