In my more complicated personal projects, I'll usually do this in comments in the code. Basically pseudocode to just expand out and then I'll either write thin

In my more complicated personal projects, I'll usually do this in comments in the code. Basically pseudocode to just expand out and then I'll either write things in between the comments that actually add the functionality or I'll just leave it at the top as a kind of "this is what this iteration does" because I'll also frequently complete an idea and then I'll have some other idea with it that requires refactoring and I'll make my second file etc!