`throws` : `async` = `try` : `await` = `rethorws` : `reasync` = `Result<T>` : `Promise<T>`

## `throws` : `async` = `try` : `await`

```swift
// Shows an action sheet and makes select one item
func actionSheet(itemes: [String]) async -> Int { ... }

// Calls an `async` function in an `async` function
func foo() async {
  let selectedIndex = await actionSheet([...])
  ...
}

// Calls an `async` function outside `async` functions
func onClick() {
  do {
    let selectedIndex = await actionSheet([...])
    ...
  } defer // does not block
}
```

## Asyncronous error handling

```swift
func download(url: URL) async throws -> Data { ... }

do {
  let data = await try download(url)
  ...
} catch error {
  ...
} defer
```

## `reasync`

```swift
do {
  let r = await [2, 3, 5].map { (x: Int) async -> Int in ... }
  ...
} defer
```