input: Write a python function to classify numbers as 'even' or 'odd'.
  assert classify([1, 2, 3, 4, 5]) == ['odd', 'even', 'odd', 'even', 'odd']
  assert classify([10, 15, 20, 25, 30]) == ['even', 'odd', 'even', 'odd', 'even']
  assert classify([7, 8, 9, 10]) == ['odd', 'even', 'odd', 'even']
output: def classify(numbers):
      return ['even' if num % 2 == 0 else 'odd' for num in numbers]