I solved the mission "The Hidden Word" and during test got an error " Your result: null". I ran code in PyCharm : there is all right. It seemsd to me there is error in the tests: https://github.com/CheckiO-Missions/checkio-task-hidden-word/blob/master/verification/tests.py

...
{
    "input": ["""Hi all!
 And all goodbye!        
 Of course goodbye.
 or not""", "haoo"],
 "answer": [1, 1, 4, 1],
},
...