input: 
                          
  def calculate_sum(arr: List[int]) -> int:
      """Calculate the sum of elements in an array of integers.
      >>> calculate_sum([1, 3, 5, 7])
      16
      >>> calculate_sum([-1, 3, -5, 7])
      4
      """   
      sum = 0
      
      for i in arr:
          sum += i
      
      return sum
    
  input_array = [1, 3, 5, 7]
  
  result = calculate_sum(input_array) 
  
  print(result) # prints 16
  
output:     sum = 0
      
      for i in arr:
          sum += i
      
      return sum