input: Write a function to determine if an array has an even or odd number of elements. If the number of elements is even, return True; otherwise, return False. If the array is empty, it is considered to have an even number of elements.
  
  assert is_array_even([1, 2, 3, 4]) == True
  assert is_array_even([5, 6, 7]) == False
  assert is_array_even([]) == True
  
output: def is_array_even(arr):
      return len(arr) % 2 == 0