# include

## Function

Import and execute BT files during runtime, and return the explicit `return` or `exit` values of the imported files.

## Syntax

```bt
include(path)
include path
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| path | String | Yes | None | The path of the BT file to be imported. |

## Return value

| Type | Description |
| ------ | ------ |
| Any/Empty | The corresponding value is returned when the include file is executed to `return` or `exit`; Empty is returned at the end of normal execution. |

## Example

```bt
fs('include-demo.bt').write('return 7')
result = include('include-demo.bt')

// Output: 7
print result

include 'include-demo.bt'
```

## Notes

- The path is parsed according to the current source code directory and project root rules.
- The include file will be compiled and cached, but the target file will be executed every time it is called.
- Function declaration will enter the current VM global environment.
- Bracketless syntax only supports statement form; please use `include(path)` when you need to assign the return value to a variable.