> For the complete documentation index, see [llms.txt](https://max-daunarovich.gitbook.io/flow-network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://max-daunarovich.gitbook.io/flow-network/introduction/values-and-types/never.md).

# Never

`Never` is the bottom type, i.e., it is a subtype of all types. There is no value that has type `Never`. `Never` can be used as the return type for functions that never return normally. For example, it is the return type of the function `panic`.

```
// Declare a function named `crashAndBurn` which will never return,
// because it calls the function named `panic`, which never returns.
//
fun crashAndBurn(): Never {
    panic("An unrecoverable error occurred")
}

// Invalid: Declare a constant with a `Never` type, but the initial value is an integer.
//
let x: Never = 1

// Invalid: Declare a function which returns an invalid return value `nil`,
// which is not a value of type `Never`.
//
fun returnNever(): Never {
    return nil
}
```