Streamline code.

src/ast/expr.rs

@@ -493,6 +493,9 @@ impl fmt::Debug for Expr {
                     }
                 }
                 f.write_str(&x.3)?;
+                if let Some(n) = x.1.index() {
+                    write!(f, " #{}", n)?;
+                }
                 if let Some(n) = i.map_or_else(|| x.0, |n| NonZeroUsize::new(n.get() as usize)) {
                     write!(f, " #{}", n)?;
                 }