Robot.GetAvailableIndex C# (CSharp) Method

        private int GetAvailableIndex()
        {
          int UsedCounterCount = UsedCounter.Count;
          for (int i = 0; i < UsedCounterCount; i++)
          {
            if (UsedCounter[i] == false)
            {
              return i;
            }
          }
    
          // Nothing available.
          return -1;
        }