One of the awesome features introduced in .NET Core 3.0 and C# 8.0 are async streams. The feature consists of two parts – async disposable, for async clean up, as well as async enumerable, for async iteration.
Normally, the C# language features are backwards compatible and can be used regardless of the runtime framework being targeted. In this particular case, however, the newly introduced types that are needed for async streams feature to work, such as for example IAsyncDisposable or IAsyncEnumerator<T>, were only added in .NET Core 3.0, restricting the usage of the features to that runtime, and later.
Let's have a look at how you can still benefit from async disposable and async enumerable on older frameworks.