library;
import self as self;
import "dart:core" as core;

extension Foo on core::Object {
  set f = self::Foo|set#f;
}
static extension-member method Foo|set#f(lowered final core::Object #this, core::int x) → void {}
static method fun(core::String? s) → void {
  let final core::String? #t1 = s in #t1 == null ?{void} null : self::Foo|set#f(#t1{core::String}, 1);
}