input: Write a python function to find the highest peak in an array.
  assert find_highest_peak([1, 3, 7, 8, 5, 6, 2, 4]) == 8
  assert find_highest_peak([10, 20, 30, 40, 50]) == 50
  assert find_highest_peak([5, 4, 3, 2, 1]) == 5
output: def find_highest_peak(arr):
      if not arr:
          return None
      highest_peak = arr[0]
      for num in arr:
          if num > highest_peak:
              highest_peak = num
      return highest_peak