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

class B extends core::Object {
  field core::Object _x = null;
  synthetic constructor •() → void
    : super core::Object::•()
    ;
  method f([core::num x = 10]) → void {
    this.{self::B::_x} = x;
  }
  method g({core::num x = 20}) → void {
    this.{self::B::_x} = x;
  }
  method check(core::Object expectedValue) → void {
    if(!this.{self::B::_x}.==(expectedValue)) {
      throw "Expected _x == ${expectedValue}; got ${this.{self::B::_x}}";
    }
  }
}
abstract class I<T extends core::Object = dynamic> extends core::Object {
  synthetic constructor •() → void
    : super core::Object::•()
    ;
  abstract method f([self::I::T x = null]) → void;
  abstract method g({self::I::T x = null}) → void;
}
class C extends self::B implements self::I<core::num> {
  synthetic constructor •() → void
    : super self::B::•()
    ;
}
static method main() → dynamic {
  self::C c = new self::C::•();
  c.f();
  c.check(10);
  c.g();
  c.check(20);
}