Proxy

function selfish(target) {
  const cache = new WeakMap()
  const handler = {
    get(target, key) {
      const value = Reflect.get(target, key)
      if (typeof value !== 'function') {
        return value
      }
      if (!cache.has(value)) {
        cache.set(value, value.bind(target))
      }
      return cache.get(value)
    }
  }
  const proxy = new Proxy(target, handler)
  return proxy
}

const logger = selfish(new Logger())