/**
Check if a URL is absolute.

@param url - The URL to check.

@example
```
import isAbsoluteUrl from 'is-absolute-url';

isAbsoluteUrl('http://sindresorhus.com/foo/bar');
//=> true

isAbsoluteUrl('//sindresorhus.com');
//=> false

isAbsoluteUrl('foo/bar');
//=> false
```
*/
export default function isAbsoluteUrl(url: string): boolean;