The problem with raw strings comes from your editors and IDEs, as they will want to add whitespace to keep the code aligned. In the middle of a raw string, that whitespace becomes part of the string itself, as you will see if you run this snippet and look at the output of the first println() call.

trimMargin() is a function available on String that removes whitespace up to a particular margin character, whether the default pipe (|) or a character that you supply.

• the documentation
• Elements of Kotlin