Refc typography spacing

Basic idea of spacing for typography.

I found that I was importing completely incorrectly in sass (even
though importing works in this way in most programming languages). I
should only import each file once unless its vars in mixins, otherwise
it will show up multiple times in the output. This means mixins all
have to be in one file.
Would you mind commenting this? I'm guessing it takes a string and converts it to an int based on its name, but I don't understand they multiplication by zero at all.

Why are there integers next to many of these functions? Depth level?