\n ↔ RegExp back ref to numbered Capture Group
aka Back-Ref, Back-Reference
References
.↔ regex Metacharacter to match any single character (excl\n& line terminator)
\n ↔ RegExp back ref to numbered Capture Groupaka Back-Ref, Back-Reference
. ↔ regex Metacharacter to match any single character (excl \n & line terminator)