class Base {
  static log = [];
  static {
    Base.log.push('base-block');
  }
  static value = (() => { Base.log.push('base-field'); return 1; })();
}

class Derived extends Base {
  static {
    Derived.log.push('derived-block');
  }
  static value2 = (() => { Derived.log.push('derived-field'); return 2; })();
}

console.log(Derived.log.join(','));

async function* gen() {
  const x = yield 1;
  const y = yield x + 1;
  return x + y;
}

async function main() {
  const it = gen();
  const a = await it.next();
  const b = await it.next(10);
  const c = await it.next(20);
  console.log(`${a.value} ${b.value} ${c.value} ${c.done}`);
}

main();

const sym1 = Symbol('id');
const sym2 = Symbol('id');

const obj = {
  [sym1]: 'first',
  [sym2]: 'second',
  regular: 'value'
};

const s = Symbol.for('shared');
const s2 = Symbol.for('shared');

console.log(
  sym1 === sym2,
  Object.keys(obj).length,
  Reflect.ownKeys(obj).length,
  s === s2,
  sym1.toString()
);

function tag(strings, ...values) {
  return strings.raw.join('|') + '::' + values.join(',');
}

const a = 5, b = 10;
console.log(tag`Sum:\n${a + b} End`);

const a = -7 % 3;
const b = 7 % -3;
const c = 2 ** 3 ** 2;
const d = (2 ** 3) ** 2;
const e = 0.1 + 0.2;
console.log(a, b, c, d, e);