new_contents: import pytest
  import linkatos.activities as message
  
  
  def test_None_event():
      event = None
      assert is_empty(event) is True
  
  
  def test_len_zero_event():
      event = []
      assert is_empty(event) is True
  
  
  def test_message_is_url():
      message = {'type': 'url'}
      assert is_url(message) is True
  
subject: Add test_activities