When it works it works. I know that you have to terminate compound/multi-line statements with a blank line in the interpreter. Blank lines are not required in python scripts. IDLE handles many things automatically. It might be style, 9. Classes in the python docs got classes with and without blank lines inside. Check out the code with the blank lines separating classes from variables, functions and iterators.
Don't know why it wouldn't work for me without the blank lines. It helps with readability for me. I use the python2 and python3 interpreter almost exclusively. I guess that is where our breakdown on this issue occurs. I don't use IDLE because it runs in its own interactive namespace. That caused problems in the beginning when I tried to run them in bash so I used the interpreter to test and copy to vim or some other IDE. In the interpreter you have to explicitly import what you need. I really don't know how IDLE handles blank lines so I can't speak on that issue.
Tried the same code with and without my corrections in IDLE and got an invalid syntax error message whien mine is declared no matter what I did. Tried the code in Codecademy and I only needed to add self to check__angles and change "Yours" to three integers to make the code work. I know the python interpreter will throw an error in this case because it has been throwing syntax errors. It stopped when I inserted the blank line to separate the class from the variable declaration and added self to the check_angles definiton. Then it gives an error about the number of arguments. Changed "Yours" to 60, 60, 60 and TRUE is returned, 60, 60, 90 and FALSE is returned.
I'm confused as to why these subtle differences in the code will produce these results being that python 2.7 is used. It has been interesting seeing the results myself. I will say that both of us are correct, depending on your programming environment. @davidkovic should have enough information to handle the subtle differences needed to code in the different environments. I know I have. When it works it works.