input: Write a function to locate the right insertion point for a specified value in sorted order.
  assert right_insertion([1,2,4,5],6)==4
  assert right_insertion([1,2,4,5],3)==2
  assert right_insertion([1,2,4,5],7)==4
  
output: def right_insertion(arr, target):
      left, right = 0, len(arr)
      while left < right:
          mid = (left + right) // 2
          if arr[mid] <= target:
              left = mid + 1
          else:
              right = mid
      return left