Lesson 6. First practice. Confusing Error

[TymKoo]

In lesson 6, if I don't write "length" parameter in the "draw_corner()" function i get this error

I am not a programmer and maybe just don't understand something but this error is really confusing. There is 0 number of arguments in "draw_corner()" function and error says "expected at most 0". So there is must be no error. It's very confusing for me as a beginner and may be as confusing for others. Also kinda stops progression with this lesson because the error doesn't help at all, just says I'm wrong when, to my understanding, I'm not. Someone may not be as confident to deny the error and use a hint instead of keep trying to understand what's really wrong.

[AlessandroRocci]

Have you written something like the image below? (even with numbers instead of length)

If so the error shown is correct. In the exercise, you are declaring (creating) the function. When you click the run button the website should run your code together with another piece of code (that you don't see) which calls (uses) the code written by you. So the error is happening because the function is declared/created saying "I don't need any data", but is called/used passing a variable in it, hence the error saying that it's too many arguments.
This said, I am another user of the website, so I am guessing some of the website workings; but I know other programming languages, so the technical part is correct. Also when you will begin using real editors/compilers the error message usually tells you the row where the code is breaking, so this confusion will not happen.
If you click on the explanation it's said that it has to do with the calling functions, I guess it could also explain that if it happens when you are declaring a function, the exercise expect you to put more parameters in the declaration