Built-in Functions - Flow Documentation

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Flow Playground

```
fun panic(_ message: String): Never
```
Terminates the program unconditionally and reports a message which explains why the unrecoverable error occurred.
```
let optionalAccount: Account? = // ...
let account = optionalAccount ?? panic("missing account")
```
```
fun assert(_ condition: Bool, message: String)
```
Terminates the program if the given condition is false, and reports a message which explains how the condition is false. Use this function for internal sanity checks.

The message argument is optional.
```
fun unsafeRandom(): UInt64
```
Returns a pseudo-random number.

NOTE: The use of this function is unsafe if not used correctly.

Follow best practices to prevent security issues when using this function.