input: Write a function to classify inputs as "fruit" or "not fruit".
  assert classify("apple") == "fruit"
  assert classify("banana") == "not fruit"
  assert classify("carrot") == "not fruit"
output: def classify(input_str):
      fruit_list = ["apple", "banana", "orange", "grape", "strawberry"]
      if input_str in fruit_list:
          return "fruit"
      else:
          return "not fruit"