input: Write a python function to check if a number is even or odd.
  assert check_type(4) == 'even'
  assert check_type(7) == 'odd'
  assert check_type(0) == 'even'
  assert check_type(13) == 'odd'
output: def check_type(num):
      return 'even' if num % 2 == 0 else 'odd'