gistfile1.rs

assign.iter()
    .zip(self.vars.iter())
    .filter(|&(_, var)| res_vars.contains(var))
    .map(|(val, var)| (val, self.table.var_cardinality(*var)))                                
    .fold((0, 1), |(sum, cs), (val, c2)| (sum + val * cs, c2 * cs));