Regex Tester & Validator

This regular expression captures the entire content of each line into a capturing group. The `m` (multiline) flag ensures the `^` and `$` anchors match the start and end of lines, respectively, while the non-greedy `.+?` matches the characters in between. It is often used in find-and-replace operations to wrap or modify every line in a text file, such as surrounding each line with quotes or adding list markers.