input: Write a function to classify whether it is raining based on temperature and humidity.
  assert classify_rain(65, 0.8) == 'raining'
  assert classify_rain(75, 0.8) == 'not raining'
  assert classify_rain(69, 0.6) == 'not raining'
  assert classify_rain(68, 0.75) == 'raining'
output: def classify_rain(temperature, humidity):
      if temperature <= 70 and humidity >= 0.75:
          return 'raining'
      else:
          return 'not raining'