Hello w3b5urf3r,
I am not quite sure if this should work this way. Look at the picture please. It seems it is connected to the possibility of changing the function arguments and not to the lowercase or uppercase letters. On the other hand, something like this is not possible neither numerically nor symbolically
[MATH=eng]f(a,b):a+b[/MATH]
[MATH=eng]a:3[/MATH]
[MATH=eng]f(a,a)=#@#[/MATH]
An error:"An item with the same key has already been added" seems to me quite strange and not comprehensible.
Regards,
Radovan

When Sisyphus climbed to the top of a hill, they said: "Wrong boulder!"