input: Write a function to determine whether an array has an even or odd number of elements by checking the value of the length of the array modulo 2. If it has an even number of elements, return True; otherwise, return False. If the array is empty, return True since 0 is considered even.
  def is_array_even(arr): 
    if len(arr)%2 == 0:
      return True
    else:
      return False
  assert is_array_even([1, 2, 3, 4])==True
  assert is_array_even([1, 2, 3])==False
  assert is_array_even([])==True
output: def is_array_even(arr): 
    if len(arr)%2 == 0:
      return True
    else:
      return False