Method add

src/07-set/set.ts:11–18

* Adds a value to the set. * @param value - The value to add * @returns true if added, false if already present * @complexity Time O(1) | Space O(1)

(value: string)

   * @complexity Time O(1) | Space O(1)
   */
  add(value: string): boolean {
    if (!this.has(value)) {
      this.#items[value] = true;
      this.#size++;
      return true;
    }
    return false;
  }

  /**
   * Adds multiple values to the set.