input: Write a function to calculate the difference between the lowest and highest value for an array of integers. The function should take an array as input and return the difference. If the array is empty, it should return 0.
  def diffHighestLowest(arr):
      if len(arr) == 0:
          return 0
      lowest = min(arr)
      highest = max(arr)
      return highest - lowest
  
  assert diffHighestLowest([12, 24, 3, 8, -1])==25
  assert diffHighestLowest([5, 1, 3, 4, 2])==4
  assert diffHighestLowest([-3, -1, -5, -2, -4])==4
  assert diffHighestLowest([10])==0
  assert diffHighestLowest([])==0
output: def diffHighestLowest(arr):
      if len(arr) == 0:
          return 0
      lowest = min(arr)
      highest = max(arr)
      return highest - lowest