input: Write a function to explain the difference between a list and a tuple in Python. If the input is a list, return "mutable", and if the input is a tuple, return "immutable". If the input is neither a list nor a tuple, return "invalid input".
  assert list_tuple_diff([1, 2, 3]) == "mutable"
  assert list_tuple_diff((1, 2, 3)) == "immutable"
  assert list_tuple_diff("string") == "invalid input"
  assert list_tuple_diff({"key": "value"}) == "invalid input"
  assert list_tuple_diff(42) == "invalid input"
output: def list_tuple_diff(input_data):
      if isinstance(input_data, list):
          return "mutable"
      elif isinstance(input_data, tuple):
          return "immutable"
      else:
          return "invalid input"