Thanks a lot. I have visualized the codeexecution step by step and Now I have undrerstood what I have been doing wrong. Tha solution for this kata is corrected. All test passed. Tahnks once again.

Mayby I will paste here my soution and you will tell me is it right?

Test Results:
Fixed tests
Test pangrams
Test Passed
Test Passed
Test Passed
Test Passed
Test Passed
Test non-pangrams
Incorrect answer for 'This isn't a pangram!': True should equal False
Incorrect answer for 'abcdefghijklm opqrstuvwxyz': True should equal False
Incorrect answer for 'Aacdefghijklmnopqrstuvwxyz': True should equal False
However whan I run this function on Pycharm the output for "Test non-pangrams" is as it should be - False