Update docs/docs/contributing/debugging.md

Co-Authored-By: Guillaume Martres <[email protected]>

Author: anatoliykmetyuk

docs/docs/contributing/debugging.md

@@ -167,7 +167,7 @@ package <empty>@<Playground.scala:1> {
 
 ## Figuring out an object creation site
 ### Via ID
-Every [Positioned](https://github.com/lampepfl/dotty/blob/10526a7d0aa8910729b6036ee51942e05b71abf6/compiler/src/dotty/tools/dotc/ast/Positioned.scala) (a trait of a `Tree`) object has `uniqueId` field. It is an integer that is unique for that tree and doesn't change from compile run to compile run. You can output these IDs from the printers (= from `show` and `-Xprint`) framework via `-Yshow-tree-ids` flag, e.g.:
+Every [Positioned](https://github.com/lampepfl/dotty/blob/10526a7d0aa8910729b6036ee51942e05b71abf6/compiler/src/dotty/tools/dotc/ast/Positioned.scala) (a parent class of `Tree`) object has a `uniqueId` field. It is an integer that is unique for that tree and doesn't change from compile run to compile run. You can output these IDs from any printer (such as the ones used by `.show` and `-Xprint`) via `-Yshow-tree-ids` flag, e.g.:
 
 ```
 dotc -Xprint:frontend -Yshow-tree-ids  ../issues/Playground.scala