It's another/newer way to do multi-line strings in Scala that allows starting all lines of the string in the same column. Scaladoc on the _stripMargins_ method:
```
For every line in this string:
  
   *  Strip a leading prefix consisting of blanks or control characters
   *  followed by `|` from the line.
```
IntelliJ readily inserts the pipe when pressing enter within the string :-)