Simple mcfunction preprocessor

I don't want fancy tools like bolt/beet currently (not sure if they are even updated to 1.21.4 yet?), all I really need currently is something similar to #define in C/C++. So, it just sets a constant variable to a given value and will replace all occurences in the code with the value (to not have magic values). Although, if bolt/beet has such functionality, please tell me