Is there any way to get a span of an ast item?

[nevinpuri]

Hi, I'm writing a parser which gets all of the comments + the corresponding ast nodes for those comments I've implemented Fold as seen below. I'm trying to get the span of an ast node, but I can't figure out how to.

I can get the span from a node, but the span only gives me access to span.lo() and span.hi() (I read somewhere that those are the positions of adjacent comments).

impl Fold for JsParser
{
    fn fold_expr(&mut self, expr: swc_ecma_visit::swc_ecma_ast::Expr) -> swc_ecma_visit::swc_ecma_ast::Expr {
        match expr {
            swc_ecma_visit::swc_ecma_ast::Expr::This(swc_ecma_ast::ThisExpr {span, ..})
            | swc_ecma_visit::swc_ecma_ast::Expr::Array(swc_ecma_ast::ArrayLit {span, ..})
            // ...

Is there any way I could get the start + end positions of an ast node?

I read #1969, but I'm confused as to which byte pos I'm supposed to pass in.