input: 
  def has_odd_or_even_elements(arr: List[int]) -> str:
      """Check whether the given array has an even or odd number of elements.
      >>> has_odd_or_even_elements([1, 2, 3, 4])
      'even'
      >>> has_odd_or_even_elements([1, 2, 3])
      'odd'
      """
      if len(arr) % 2 == 0:
          return 'even'
      else:
          return 'odd'
  
output:     if len(arr) % 2 == 0:
          return 'even'
      else:
          return 'odd'