{"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"///"}]}
    /// with the constraint `'?b: 'a` (`'a <: '?b`), where `'a` is some known
    /// value `b_data` to the lub of `b_data` and `a_region`. The corresponds
    /// region and `'?b` is some region variable.