input: Write a python function to classify a list of numbers into positives and negatives.
  assert classify_numbers([1, -2, 3, -4, 5, -6, 7, -8, 9, -10]) == ([1, 3, 5, 7, 9], [-2, -4, -6, -8, -10])
  assert classify_numbers([-1, -2, -3, -4, -5]) == ([], [-1, -2, -3, -4, -5])
  assert classify_numbers([0, 10, -10, 20, -20]) == ([0, 10, 20], [-10, -20])
output: def classify_numbers(numbers):
      positives = [num for num in numbers if num >= 0]
      negatives = [num for num in numbers if num < 0]
      return (positives, negatives)