Concatenating Partial Path in Jade Template

I have a Jade template on an Express project that looks something like this (simplified for brevity):

!!! 5
head
    ...
body
    include path/to/partial

What I am trying to figure out is dynamically generate the partial's path so that I could easily swap out the partial based on a server variable. Since path/to/partial isn't a string, is there a way to provide the concatenation?