In addition to some of the other answers about the match statement, mCoding has this excellent video[0] explaining the match statement, specifically using it to match complex AST trees, like Refurb does. Note, not all of these checks use the match statement[1], sometimes it is more verbose to use a match statement vs a normal if/else statement.

[0]: https://youtu.be/ASRqxDGutpA?t=470 [1]: https://github.com/dosisod/refurb/blob/master/refurb/checks/...