Method variadic

src/expr/src/interpret.rs:538–540

(&self, func: &VariadicFunc, exprs: Vec<Self::Summary>)

    }

    fn variadic(&self, func: &VariadicFunc, exprs: Vec<Self::Summary>) -> Self::Summary {
        self.evaluator.variadic(func, exprs)
    }

    fn cond(&self, cond: Self::Summary, then: Self::Summary, els: Self::Summary) -> Self::Summary {
        self.evaluator.cond(cond, then, els)