Optional
Regex options. String with any combination of the following characters: d,g,i,m,s,u,y. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags
The Regular expression to search with. This can just be a simple string if desired.
Regex options. String with any combination of the following characters: d,g,i,m,s,u,y. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags