input: Write a python function to determine if a hexadecimal number is even or odd.
  assert even_or_odd("AB3454D") == "Odd"
  assert even_or_odd("ABC") == "Even"
  assert even_or_odd("AAD") == "Odd"
output: def even_or_odd(hex_num):
      return "Even" if int(hex_num, 16) % 2 == 0 else "Odd"