SomeUnicodecharactersare[fullwidth](https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms) and use double the normal width. [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code) are stripped and doesn't affect the width.
@example
```
importstringWidth=require('string-width');
stringWidth('a');
//=> 1
stringWidth('古');
//=> 2
stringWidth('\u001B[1m古\u001B[22m');
//=> 2
```
*/
(string:string):number;
// TODO: remove this in the next major version, refactor the whole definition to:
// declare function stringWidth(string: string): number;