Async Await is a feature.
In computer programming, the async/await pattern is a syntactic feature of many programming languages that allows an asynchronous, non-blocking function to be structured in a way similar to an ordinary synchronous function. It is semantically related to the concept of a coroutine and is often implemented using similar techniques, but is primarily intended to provide opportunities for the program to execute other code while waiting for a long-running, asynchronous task to complete, usually represented by promises or similar data structures. The feature is found in C# 5.0, Python 3.5, Hack, Dart, Kotlin 1.1, and JavaScript, with some experimental work in extensions, beta versions, and particular implementations of Scala, Rust, and C++.. Read more on Wikipedia...
Languages without Async Await include Ruby, Jule
Languages with Async Await include JavaScript, C#, Dart, X10
async doSomething => await somethingElse()
public async Task<int> FindPageSize(Uri uri)
{
byte[] data = await new WebClient().DownloadDataTaskAsync(uri);
return data.Length;
}