Function unescapePattern

unescapePattern(pattern?: string | null): string | null | undefined
Returns a regex pattern that unescaped the given pattern
Parameters
- Optionalpattern: string | null
  The pattern to inspect
Returns string | null | undefined
a regex pattern that unescaped the given pattern
Author
David Hsing
Example
```
unescapePattern('\\\\');    // '\\'
unescapePattern('\\+\\-=');    // '+-='
```