Method apply1

core/src/parser.rs:206–217

(
            exprs: &mut Vec<Expr>,
            pos: LineCol,
            f: fn(Box<UnaryOpSpan>) -> Expr,
        )

    /// Pops operands from the `expr` stack, applies this operation, and pushes the result back.
    fn apply(&self, exprs: &mut Vec<Expr>) -> Result<()> {
        fn apply1(
            exprs: &mut Vec<Expr>,
            pos: LineCol,
            f: fn(Box<UnaryOpSpan>) -> Expr,
        ) -> Result<()> {
            if exprs.is_empty() {
                return Err(Error::Bad(pos, "Not enough values to apply operator".to_owned()));
            }
            let expr = exprs.pop().unwrap();
            exprs.push(f(Box::from(UnaryOpSpan { expr, pos })));
            Ok(())
        }

        fn apply2(
            exprs: &mut Vec<Expr>,