thanks,i can see it in my phone.maybe my computer Chrome has some problems
,and i don't want to know why.
thanks .i will close the question

I can not see the picture that under “Here is a picture to help explain:”，i think the picture`s src is "https://i.imgur.com/tGeWQVq.png\",
i want to know other people can see this picture or not.And how should i do to see this picture

I am happy to find this kata and solve it,it is great,thank you

Thank you for your answer, I know why my code has a problem.
And I think this is question,Do I need to change the label or delete it?

"If a pattern is invoked which does not exist, your interpreter should throw."
I want to know how to throw an error in python
when my code is "raise SyntaxError('this is the error message')" in python
the test will tell me "stderr"
What should I do to pass the test "should throw an error when a non-existing pattern is invoked"

The behavior of round () for floats can be surprising : for example , round ( 2.675 , 2 ) gives 2.67 instead of the expected 2.68 . This is not a bug : it ' sa result of the fact that most decimal fractions can ' t be represented exactly as a float . See Floating Point Arithmetic : Issues and Limitations for more information .

beautiful