I have the next bext in the 2-nd part of tests:

Test14
expected:<[U]> but was:<[]>

What does it mean? All of test in the 2-nd part (exception for this Test14) are completed

So it's just my inattention. It's something funny to feel that my mistake was not in the code but in the ability to read the terms)

Thanks for your reply because of I thought that 2-3 hours only on finding mistake were without effect.

Yeah , it was truth about global variable.

I choose it as issue because of my experiance. I thought that it's an issue, not a question.

Thanks for your useful reply)

in the test there is text:

                       Incorrect result for "aabb"
                       Expected: equal to { 'a': 2, 'b': 2 }
                       Actual: { 'a': 4, 'b': 2 } 

but my program returns 'a': 2, 'b': 2

maybe someone has the same problem?