code: def peakIndexInMountainArray(self, arr: List[int]) -> int:
      start, end = 0, len(arr) - 1
  
      while start < end:
          mid = (start + end) // 2
          if arr[mid] < arr[mid + 1]:
              start = mid + 1
          else:
              end = mid
      return start
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.peakIndexInMountainArray(arr) and returns: start