{"ast_node_type":"impl","tokens":[{"end":69,"kind":"keyword","start":0,"text":"///"}]}
    /// Foo<'a> = impl Trait<Item = &'a u32>`, but `impl Trait<item =
    /// Trait<Item = &u32>` expands to an opaque type like `type
    /// dyn Bar>` expands to `type Foo = impl Trait<Item = dyn Bar +