# XO0168: statement (let, expression, ...) at top level

A file holds only `use` declarations and declarations (`fn`, `struct`, `enum`, `interface`, `type`, `const`, `test`). Statements such as `let`, assignments, and expressions are allowed only inside a function or test body. A module level value is a `const`. See core 15 (File).

## Example

```xo
let max_users = 10

fn f() -> Int { max_users }
```

## Fix

```xo
const MAX_USERS = 10

fn f() -> Int { MAX_USERS }
```

Run `xo explain XO0168` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).