selector	role	matching syntax
(arg)	argument positions in call sites and function parameters	-
(call)	function calls	foo() value.method() macro!(...)
(enum)	enum declarations and scoped variant references	enum Color {} Color::Red
(fun)	function declarations	fn foo() {} async fn foo() {}
(id)	identifier references	-
(mem)	field access expressions	value.field value.field.subfield
(mod)	module (source file)	-
(num)	numeric literals	-
(str)	string literals	-