You are right. The documentation, that I know, is clear. Anyway in this case "is" and "==" provides the same outcome and this is my remark, that I called bug, wrongly. The reason is the nature of print(), as function, that always remains always NoneType with only the value None.  Nevertheless, print, as method, could be referred to the object. 
This is my goofy remark about the contraddiction between the message of the communication by print method and the nature of the communication by print function. 
Therefore, the monitor tells you that two things are not equals because they are two different ways to say the same message. Thanks a lot for the patience