LJ::fill_var_props — S1 utility function to interpolate %%variables%% in a variable. If a modifier is given like %%foo:var%%, then LJ::fvp_transform is called.
LJ::fill_var_props(vars, key, hashref);
vars. hashref with keys being S1 vars
key. the variable in the vars hashref we're expanding
hashref. hashref of values that could interpolate.