input: Write a python function to perform binary search on a sorted array and return the index of the target element.
  assert binarySearch([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 0, 9, 5) == 4
  assert binarySearch([10, 20, 30, 40, 50, 60, 70], 0, 6, 30) == 2
  assert binarySearch([2, 4, 6, 8, 10, 12, 14], 0, 6, 7) == -1
output: def binarySearch(arr, low, high, target):
      while low <= high:
          mid = (low + high) // 2
          if arr[mid] == target:
              return mid
          elif arr[mid] < target:
              low = mid + 1
          else:
              high = mid - 1
      return -1