}

    /**
     * Sets the concurrency level that will be used by the to-be-built {@link Interner}.
     *
     * @see MapMaker#concurrencyLevel(int)
     */
    public InternerBuilder concurrencyLevel(int concurrencyLevel) {
      this.mapMaker.concurrencyLevel(concurrencyLevel);
      return this;
    }

    public <E> Interner<E> build() {
      if (!strong) {
        mapMaker.weakKeys();
      }

    }

    /**
     * Sets the concurrency level that will be used by the to-be-built {@link Interner}.
     *
     * @see MapMaker#concurrencyLevel(int)
     */
    public InternerBuilder concurrencyLevel(int concurrencyLevel) {
      this.mapMaker.concurrencyLevel(concurrencyLevel);
      return this;
    }

    public <E> Interner<E> build() {
      if (!strong) {
        mapMaker.weakKeys();
      }