input: Write a function to calculate the sum of a given list of numbers and print the result. If the list is empty, print 0.
  def sum_list(arr):
      """Calculates the sum of a given list of numbers and prints the result.
      
      Args:
          arr (list): List of numbers.
      """
      if not arr:
          print(0)
          return
      result = sum(arr)
      print(result)
  
  assert sum_list([1, 2, 3, 4, 5])==None  # Output should be printed as 15
  assert sum_list([0, -1, 1])==None  # Output should be printed as 0
  assert sum_list([])==None  # Output should be printed as 0
output: def sum_list(arr):
      if not arr:
          print(0)
          return
      result = sum(arr)
      print(result)